Ultimate guide on ”Invoicing in the European Union”

Required Information on a VAT Invoice

• Date of issue – the date the invoice is issued. [stripe.com]
• Invoice number – a unique sequential number that identifies the invoice. This ensures each invoice can be uniquely referenced (no duplicates). [stripe.com]
• Supplier’s name, address, and VAT identification number – the seller’s full legal name and address, and their VAT registration number under which the supply is made. [stripe.com]
• Customer’s name and address – the buyer’s full name (or company name) and address. (Note: For B2C sales, the customer’s details might not be required on a simplified invoice or receipt, but for standard B2B invoices it is required.) [stripe.com]
• Customer’s VAT identification number – if the customer is liable for the VAT on the transaction or if it’s an intra-Community supply. For example, in a reverse-charge supply or an intra-EU sale of goods (which is zero-rated), the customer’s VAT number must appear. [stripe.com]
• Description of goods or services – a clear description of what is being supplied. This should include the nature and quantity of goods, or the type and extent of services. It should be detailed enough to identify the supply. [stripe.com]
• Date of supply (or completion) – if different from the invoice date, you need to mention when the goods were delivered or the service completed. If payment was received in advance (like a deposit), the date of payment might also need to be indicated. [stripe.com]
• Unit price and any discounts – the price per unit (exclusive of VAT) and any discounts or rebates that are not included in the unit price. This shows how the net amount was calculated. [stripe.com]
• Taxable amount per rate – the net amount (value excluding VAT) chargeable for the goods/services at each VAT rate or exemption category. If different items have different VAT treatments, each needs its own line showing the net amount for that treatment. [stripe.com]
• VAT rate applied – the percentage rate of VAT for each item or line (e.g. 0%, 5%, 20%, etc.). If an item is exempt or zero-rated, that should be indicated (often by a note or using 0% as the rate with an explanation). [stripe.com]
• VAT amount – the amount of VAT, in the local currency, for each VAT rate and a total VAT amount for the invoice. On a typical invoice, you’ll list the VAT per line or per rate and then sum up to a total VAT at the bottom. [stripe.com]
• Total gross amount – although not explicitly listed in the directive’s required fields, it’s standard to show the total amount including VAT, for completeness (net amount + VAT).
• Special mentions when applicable – the invoice should include specific wording if a special VAT situation applies: for example:
  • If the sale is VAT-exempt, include a reference to the relevant article of the VAT Directive or national law, or simply state “VAT exempt” (along with the reason/category). [eur-lex.europa.eu]
  • If the reverse charge applies (meaning the customer will self-account for the VAT), the invoice must state “Reverse charge”. [eur-lex.europa.eu]
  • If the invoice is issued by the customer (self-billing), it must state “Self-billing”. [eur-lex.europa.eu]
  • If a margin scheme (e.g. second-hand goods or travel agents) is used, it should say which scheme (e.g. “Margin scheme – second-hand goods”). [eur-lex.europa.eu]
  • If the supplier is using cash accounting (paying VAT upon payment receipt), it should state “Cash accounting” (this is a national option, indicated in some countries). [eur-lex.europa.eu]

When Invoices Should Be Issued (Timing) and Sent Out

• General Rule – At time of supply: As a best practice, issue the invoice at the moment the goods are delivered or the service is completed (or shortly thereafter). Many companies invoice immediately or within a few days of delivery.
• Latest Deadline (15th of the next month for many B2B transactions): EU law sets a specific latest deadline for certain transactions. For intra-EU supplies of goods (which are zero-rated) and for domestic supplies where the customer is liable for the VAT (reverse charge), an invoice must be issued by the 15th day of the month following the month in which the supply took place. For example, if a service was provided on March 20 to a business customer under reverse charge, the invoice should be issued no later than April 15. This rule harmonizes the timing for cross-border scenarios. [eur-lex.europa.eu]
• Domestic transactions: For other cases (like standard domestic sales where the supplier charges VAT), Member States can set their own rules on how quickly an invoice must be issued. Many countries also use the “by the 15th of next month” rule, or require invoicing by the time of filing the VAT return for that period. Always check local requirements, but they usually align closely with the EU norm. [eur-lex.europa.eu]
• Advance payments: If you receive payment or a part-payment before delivering goods or completing a service (and that payment makes VAT become chargeable), you typically need to issue an invoice at the time of that payment (at least for the amount paid). This is because VAT becomes due when payment is received for that portion.
• Continuous supplies: If services or goods are supplied on an ongoing basis, at least one invoice needs to be issued at regular intervals (usually monthly) to cover the ongoing supply.
• Sending the Invoice to the Customer: Once prepared, the invoice must be delivered to the counterparty (the customer). VAT invoices are meant to be communicated – the buyer needs the invoice as their record. “Issuing an invoice” inherently includes providing it to the recipient. In practice, this can be done by postal mail, email with a PDF attachment, through an electronic invoicing system, or any other agreed method. The key is that the customer receives it in a form they can keep. Typically, the supplier keeps a copy and sends the original (or a duplicate) to the customer. It’s not enough to just record it in your own system; the customer must have the invoice. Indeed, the supplier is responsible for issuing and sending the invoice (unless using self-billing). [avalara.com]
• Consequences of late invoicing: Failing to issue an invoice on time can violate VAT regulations. If an invoice is issued late, some countries might impose a fine for late invoicing. Moreover, VAT becomes chargeable by the legal deadline regardless of whether you invoiced – meaning if you delay invoicing beyond the allowed time, you could end up having to account for the VAT as if you had invoiced by the deadline anyway. Timely invoicing prevents mismatches in VAT reporting.

Why Invoices are Needed (VAT Significance)

• Evidence for Tax Credit (Input VAT Deduction): For a VAT-registered business, holding a valid VAT invoice is usually a prerequisite to claim input VAT deduction on a purchase. Under EU law, you generally cannot deduct the VAT you paid on business expenses unless you have a proper invoice from the supplier. The invoice provides the evidence that VAT was charged to you, and thus you’re entitled to reclaim it (assuming the goods/services are used for your taxable business activities). Tax authorities will check invoices to confirm that any VAT claimed on a VAT return matches an actual invoice. No invoice = high likelihood of the deduction being disallowed until an invoice is obtained or the error is resolved. [eur-lex.europa.eu]
• Record of VAT payable: For the seller, the invoice documents how much VAT you need to remit to the government. Each invoice contributes to the total output VAT you declare. It’s a formal record that you charged a customer VAT amount X on date Y. Invoices help ensure you don’t forget to report a sale, and they provide the details needed for your VAT ledger.
• Legal Obligation & Audit Trail: Issuing invoices is a legal requirement for most B2B transactions in the EU. They create an audit trail. Tax authorities rely on invoices to verify that VAT has been properly charged and can cross-reference sales and purchases between companies. For example, if your company’s invoices show €1,000 VAT charged to Customer A, the tax authority can check Customer A’s records to ensure they claimed €1,000 as input VAT – the invoice ties the two records together. This mutual record-keeping is a cornerstone of VAT control mechanisms. [taxation-c….europa.eu] [avalara.com], [avalara.com]
• VAT Neutrality Principle: The design of VAT is meant to be neutral for businesses, meaning VAT should not be a cost to companies (it’s borne by the final consumer). This neutrality is maintained by the mechanism of charging and deducting VAT at each stage of supply. Invoices are the instruments through which this mechanism functions. They ensure that the VAT one business adds to a sale can be picked up as a credit by the purchaser. The European Court of Justice (ECJ) has repeatedly emphasized that the right to deduct VAT (and thereby maintain neutrality) is fundamental. Thus, having proper invoices is part of safeguarding that right. However, the ECJ also stresses substance over form: if an invoice has minor errors, that alone shouldn’t defeat a legitimate deduction claim, as long as the basic facts of a real taxable transaction are present (more on this in the next section).
• Communication and Clarity: Invoices also serve a practical communication purpose. They tell the customer how much to pay and by when, what was provided, and how much VAT was charged. Internally, they help a business keep track of accounts receivable and payable. For VAT specifically, a clear invoice helps the customer know how to record the VAT (as payable under reverse charge, or as reclaimable input VAT, etc., depending on the scenario). It also indicates if any special VAT treatments were applied (so the customer doesn’t mistakenly deduct VAT that wasn’t actually charged, for instance).
• Requirement for certain transactions: In some cases (like certain cross-border sales to consumers, as noted earlier), an invoice might not be mandatory by EU law. But for internal teams and best practice, it is advisable to always have an invoice or receipt for every transaction. It creates a complete record and avoids confusion. Internally, having a consistent invoicing practice means your team can always answer “do we have an invoice for this sale/purchase?” with yes, which is important for accounting and audits.

Consequences of Incorrect Invoices

• Customer’s VAT deduction at risk: The immediate consequence of an error on an invoice is usually felt by the customer (buyer). Tax authorities may reject an input VAT deduction if the supporting invoice is non-compliant. For example, if the invoice is missing the supplier’s VAT number, or the VAT amount isn’t stated, or it doesn’t mention “reverse charge” when needed, a tax auditor can say the invoice isn’t valid for deduction. The customer would then have to go back to the supplier to get a corrected invoice. Until a proper invoice is obtained, the customer might be denied the VAT credit or at least have it delayed. This can impact cash flow and cause administrative headaches for both parties. [eur-lex.europa.eu]
• Need for corrections (Credit/Debit notes): Any significant error typically requires issuing a corrective document (credit note or debit note). That’s extra work. Suppose you invoice €10,000 instead of €1,000 by mistake, or you charge VAT when it should have been reverse charged. You will need to promptly issue a credit note to cancel or adjust the wrong invoice (see next section on how credit/debit notes work). During the period before correction, your records and the customer’s records are out of sync. In some cases, the customer might even withhold payment until a corrected invoice is received (particularly if the error affects their ability to deduct VAT).
• Supplier’s VAT reporting errors: If the invoice error means you overcharged VAT, you might have declared too much VAT in your return. That’s less of a legal issue (tax authorities don’t mind if you overpay, though you’ll want to get it back via correction), but if you undercharged or failed to charge VAT when you should have, you have a compliance issue. You remain liable for the correct VAT even if your invoice showed less. For instance, if you mistakenly treated a sale as zero-rated and issued an invoice with no VAT when standard VAT should have applied, the tax authority can come to you for the unpaid VAT. You’d then need to possibly issue a debit note to the customer to collect the VAT or otherwise rectify the situation. Errors can thus lead to underpayment of VAT to the government, which carries risk of penalties or interest.
• Penalties and fines: Many EU countries impose penalties for not complying with invoicing rules. If your invoice doesn’t meet legal requirements, you could be fined (the severity depends on the country and the nature of the error). Common issues that incur fines include: not issuing an invoice when required, issuing it late, missing mandatory fields, or mis-stating VAT. While a one-off minor mistake (like a typo) is often just fixed without penalty, systematic failures or anything that looks like an attempt to evade tax will draw penalties. Also, if an invoice error leads to an incorrect VAT return (like underpaying VAT), expect a potential penalty for the underpayment in addition to having to pay the VAT difference.
• Loss of audit trail: An incorrect invoice can break the clear audit trail that should link the transaction to the tax accounts. For example, if an invoice has the wrong date or invoice number sequence, it could raise questions in an audit about whether some invoices are missing or duplicated. If an invoice doesn’t reference the correct customer or the correct amount, it may be hard for an auditor to tie that invoice to a contract or payment. These discrepancies can prolong audits or invite deeper scrutiny.
• ECJ case law perspective (substance over form): The European Court of Justice has ruled in multiple cases that a purely formal error on an invoice should not automatically defeat a VAT deduction if the fundamental conditions for that deduction are met (i.e., the supply actually happened, the buyer is a taxable person, etc.). The principle of VAT neutrality means that tax authorities shouldn’t use invoice mistakes as an excuse to deny input VAT if the mistake is minor and can be corrected. For instance, if an address is slightly wrong or a VAT number had a typo, and you can provide the correct info, the deduction should be allowed in the end. However, in practice, the company will still have to fix the invoice or supply additional evidence. The ECJ has also made it clear that tax authorities cannot demand more information on an invoice than what the VAT Directive itself requires. This protects businesses from overly strict national rules. Despite these principles, relying on case law after the fact is not a strategy – it’s there as a safety net. The goal is to get the invoice right the first time to avoid any dispute at all.
• Extreme cases – fraud signals: In worst-case scenarios, persistent invoicing errors can appear suspicious. If invoices are missing major elements (like no VAT number, or using incorrect rates systematically), tax authorities might question whether the errors are intended to cover something up. Cases of missing or fake invoices are often connected to VAT fraud (e.g., a business that cannot produce a valid invoice for a claimed expense might be suspected of fictitious claims). While a simple mistake by a genuine business is not fraud, repeated mistakes could put a business on a tax authority’s radar.

Credit Notes and Debit Notes (Handling Invoice Corrections)

• Credit Note: This is issued to reduce the amount charged on an original invoice. Common reasons:
  • Goods were returned or services were not as delivered, and the customer is due a refund or reduction.
  • A pricing error on the original invoice (overcharge) needs correction.
  • A discount or rebate was agreed after the original invoice was sent.
  • VAT was charged mistakenly (e.g., should have been reverse charge or exempt).
  A credit note typically shows a negative amount for the adjustment. For example, if the original invoice was €1,000 + €200 VAT, and goods worth €500 are returned, a credit note would show -€500 net and -€100 VAT (assuming 20% VAT) to offset that portion.
• Debit Note: This is the opposite, used to increase the amount charged if the original invoice was too low. Reasons might include:
  • You forgot to invoice an item or undercharged on the original.
  • After issuing the invoice, you realized extra work was done outside the scope, billable separately.
  • VAT was not charged when it should have been (so now you need to charge it).
  A debit note will show additional positive amounts that the customer owes on top of the original invoice. It’s effectively a supplemental invoice.

• An identifying document number and date of issue (they are documents in their own right).
• The name, address, and VAT number of the supplier and customer (same parties as the original invoice).
• Reference to the original invoice: This is critical. The credit/debit note must specify which invoice is being adjusted (by date and number, for instance) and ideally briefly why. EU rules say there should be a “specific and unambiguous reference” to the initial invoice being corrected. For example, a credit note might say: “Credit Note referencing Invoice #12345 dated 01/09/2025, for return of goods.” [taxation-c….europa.eu]
• The adjustment to the taxable amount and VAT: e.g., “Product return – Quantity 10 @ €50 = €500, VAT 20% = €100, credited.” In effect, it will list negative line items (for a credit) or additional line items (for a debit) with the corresponding VAT.
• Reason or description: a short description of why the credit/debit note is issued (goods return, pricing error correction, etc.), which ties to the reference invoice.
• Any other relevant mention: If any special scheme or reverse charge was on the original, the same logic applies. Usually the credit note mirrors the VAT treatment of the original invoice line being adjusted.

• For the supplier, a credit note with VAT is like negative output VAT (reducing the VAT that needs to be paid to the government or increasing a refund claim). A debit note is additional output VAT.
• For the customer, a credit note means negative input VAT (they must reduce their VAT claim or pay back that amount if they already claimed it). A debit note means additional input VAT they can claim (if it’s a normal sale) or additional VAT they owe (if it was reverse charge or if the debit note is to charge VAT that was missed).

Acceptable Invoice Formats (Paper vs Electronic) and Sending Method

• Paper invoices: This is the traditional format – a physical hard copy. Paper invoices must obviously contain all the required info as discussed. There’s no additional formal requirement for paper beyond the content itself. Paper invoices should be delivered to the customer (by post or in person) and a copy stored by the issuer.
• Electronic invoices: An e-invoice can be a PDF sent by email, an invoice delivered through an EDI (Electronic Data Interchange) system, an XML invoice following a standard like PEPPOL, or even a structured invoice available on a portal. According to EU Directive rules, a natively electronic invoice is acceptable as long as the customer agrees to receive invoices electronically and the invoice’s authenticity of origin, integrity of content, and legibility are ensured. In practice, “authenticity and integrity” means you have controls to ensure the invoice hasn’t been tampered with and that it indeed comes from who it says (e.g., from the supplier). Common ways to ensure this include: [taxation-c….europa.eu] [eur-lex.europa.eu]
  • Sending from a company email and maybe having PDF security, or
  • Using recognized e-invoicing platforms that maintain audit trails, or
  • Even advanced methods like electronic signatures or EDI agreements, although those are not mandatory if other reliable controls exist. [eur-lex.europa.eu]
  The requirement for customer acceptance is important: you should have, at least implicitly, an agreement that the customer is okay with receiving invoices electronically (these days, most are). Some businesses include a clause in contracts or on their website that by doing business, the customer consents to e-invoicing. If a customer insists on paper, then you should send paper. (Note: EU law is evolving – from 2024 onwards, some countries are moving to mandate e-invoicing for B2B, and by 2028-2030 the EU is planning to allow e-invoices without recipient approval. But as of now, agreement is needed in general.)
• Formats: There is flexibility. Acceptable electronic formats can be PDF, Word, image, etc., but also structured formats (like XML or UBL) that allow automated processing. Starting in 2019, EU public administrations must accept a structured format for B2G invoices, which influences what’s acceptable for B2B as well. For internal standards: a PDF invoice sent by email is usually fine for most cases and is commonly used. More advanced formats may be used with big trading partners or internal systems. [taxation-c….europa.eu]
• Ensuring Legibility and Storage: Whatever format, invoices must remain legible for the required storage period (usually 6-10 years depending on country). If you use electronic, make sure you have systems to archive those invoices and that they can be retrieved and read on request. Digital storage is generally allowed anywhere (even in a different country) as long as access can be provided to authorities if needed. [taxation-c….europa.eu]
• Sending the Invoice: If paper, you mail it (or courier, etc.). If electronic, you email it, or send via EDI, or upload to a customer’s billing portal, etc. The method can vary:
  • Email: Attaching the invoice as PDF is very common. The email itself can serve as a cover note and the PDF as the formal invoice.
  • EDI / Web Portal: Some larger companies use integrated systems (for instance, you upload the invoice to their procurement portal, which then counts as delivered).
  • Print and mail: Still used in more formal industries or where e-communication isn’t agreed.
• Do we need to also send a paper copy if we e-mail it? No, not under EU law. One format is enough as long as it’s agreed. Sending duplicates in different formats can actually confuse things (customer might think it’s a separate invoice if not marked clearly). So normally, choose one: either electronic or paper. If you send an e-invoice, do not send a paper original as well, unless specifically requested and marked “copy.”
• What about invoices that are prepared and “reported” to tax authorities electronically (like clearance systems)? In some countries (e.g., Italy) there’s a live reporting of invoices to the tax authority. Even in those cases, you still must deliver a copy to the customer (in Italy’s case, through a government system that also routes it to the customer). The principle holds: the counterparty gets it. Internal standard: if we ever operate in such jurisdictions or under future “digital reporting” rules, we will ensure compliance with those, but still make sure customers receive their invoices.

Special Invoicing Scenarios: Self-Billing, Simplified Invoices, and Summary Invoices

Self-Billing

• When/Why used: Typically, self-billing is agreed upon when the customer has a better ability to determine the value of the supply or for convenience. For example, in a manufacturing context, a company buying small lots of recyclable material from many suppliers might self-bill those suppliers periodically to streamline paperwork. Another example is internal cross-charges within a company group: the receiving entity might self-bill to ensure the format and data meet internal standards.
• Requirements: EU law (Article 224 of the VAT Directive) says self-billing is allowed only if there is a prior agreement between the supplier and customer and a procedure for the supplier to accept each invoice issued by the customer. In practical terms: [eur-lex.europa.eu]
  • The supplier and customer sign a self-billing agreement. This usually specifies that the customer will issue invoices on the supplier’s behalf for all supplies of X type, for a certain period, etc., and that the supplier will not issue their own invoices for those supplies.
  • The supplier agrees to accept the invoices the customer prepares. Often the agreement will say something like “the supplier undertakes to accept all self-billed invoices unless it notifies objections within X days.”
  • Each self-billed invoice must state “Self-billing” on it, to clearly indicate why the invoice was not issued by the supplier. [eur-lex.europa.eu]
  • The invoice still uses the supplier’s name and VAT number as the issuer (even though the customer prepared it). Some Member States require a phrase like “Issued by customer on behalf of [Supplier Name]” to be present. [eur-lex.europa.eu]
• VAT treatment: The VAT on a self-billed invoice is handled as if the supplier issued it. The supplier must account for that output VAT in their returns, and the customer (if it’s a normal taxable supply) will deduct it as input VAT. So both parties need to record the self-billed invoices in their books. The supplier needs a copy of each self-billed invoice for their records (oftentimes, the customer sends a copy or at least a summary periodically).
• Internal use: If we engage in self-billing (either us self-billing our suppliers, or a customer self-billing us), we must ensure agreements are in place and our systems are set up to accept or send invoices accordingly. It’s important that no duplicate invoicing happens (i.e., the supplier doesn’t also issue an invoice for a transaction that the customer self-bills, otherwise two invoices exist for one supply).
• Risks: The main risk is loss of control by the supplier over invoicing. If the customer makes a mistake on a self-billed invoice, it’s still the supplier’s VAT at stake. That’s why the procedure for acceptance is required – the supplier needs to review and make sure the invoices are correct. If our company is the one being self-billed, we should have someone check those incoming self-billed invoices against our delivery records to confirm they’re right. Another risk is if the self-billing agreement lapses or is cancelled and invoices get issued incorrectly; strong communication is needed there.

Simplified Invoices

• When allowed: The EU VAT Directive (Article 220a) allows simplified invoices for transactions where the amount is low (up to a certain threshold, e.g., €100) or in specific cases determined by each country (like vending machine sales, toll tickets, or other scenarios where issuing full invoices is impractical). Most countries set the threshold for a simplified invoice around €100 or €150 (it can vary, e.g., some may allow up to €250). Also, if an invoice is a credit note, it can often be in simplified form referencing the original invoice. [stripe.com]
• What’s different: A simplified invoice does not need to contain all the information of a full invoice. Typically, it must include at least:
  • Date of issue, [stripe.com]
  • Identification of the supplier (name, address, VAT number), [stripe.com]
  • Description of goods/services (and quantity), [stripe.com]
  • Total amount payable including VAT, or the VAT amount (so that the VAT can be determined). [stripe.com]
  It might not need the customer’s name/address, and might not need a sequential number in the same strict sense (though usually there will still be some number on it). It can be something like a cash register receipt that says “Total including VAT: €120, VAT included: €20” etc., with the supplier’s details on it.
• Use cases: Simplified invoices are common in retail. For example, if an employee travels and buys office supplies for €30 and gets a receipt, that receipt can potentially serve as a simplified invoice for VAT reclaim (as long as it shows VAT info and the company’s VAT number isn’t required for such a small purchase). Our internal teams might encounter simplified invoices when dealing with petty cash expenses or miscellaneous purchases. For sales, unless we operate retail or small transactions, we as a supplier might not use simplified invoices frequently. If we do, we must ensure we’re within the allowed scope (like under the amount threshold, etc.).
• Important: A simplified invoice cannot be used for cross-border supplies or where the customer is liable for VAT (reverse-charge). In those cases, a full invoice is always needed regardless of the amount. Simplified invoices are mostly for straightforward domestic sales of negligible value or special cases (like parking garage tickets, etc.).
• VAT deduction: If our company receives a simplified invoice (say a small receipt) and it contains the necessary info (supplier, VAT amount, etc.), tax authorities should accept it for input VAT deduction. However, if it’s missing something essential (like VAT amount), then we might need additional proof or we simply can’t reclaim that VAT. So when possible, even for small things, getting a full invoice is safer. But if not, a simplified one should suffice for small amounts.

Summary Invoices

• EU rules: The VAT Directive expressly allows businesses to issue summary invoices covering multiple separate supplies, as long as those supplies took place in the same calendar month. Member States even have the option to allow summary invoices for longer periods (though in practice monthly is the standard, and some might allow, say, a quarterly summary in certain cases). [eur-lex.europa.eu]
• Benefits: This can significantly reduce the number of invoices. For example, if Company A delivers goods to Company B every week (4 times in a month), instead of 4 invoices, Company A could issue one invoice at month-end summarizing all 4 deliveries. It saves administrative work and consolidates the VAT reporting for those transactions.
• What it looks like: A summary invoice will still have one invoice number and date (the date likely being the end of the period or the date of issuance). It will list each supply (with its date, description, amount, VAT) as separate lines or sections. Essentially it’s like combining multiple invoices into one document. The invoice date for VAT timing purposes is at the end, but each supply’s date is noted. If all the supplies are in the same VAT period (month), VAT becomes chargeable for each as it happened, but you’re allowed to issue the invoice by that later date covering them all. If any supply in the list had a different VAT treatment, that’s handled per line (e.g., if one delivery was at 5% VAT and others at 20%, they’re shown accordingly).
• Requirements: Just ensure all the information required for each supply is included in the summary. This means the description, quantity, date of each supply, the VAT rate and amount for each. The summary invoice should logically total up everything. If using summary invoices, make sure none of the individual supplies slip through un-invoiced; it’s easy to forget one, so good record-keeping is needed.
• When to issue: Since by EU law VAT of all supplies must be in the same month, typically you’d issue the summary invoice at the end of that month (and by the 15th of the next month at the latest, as per the rule). Some businesses do bi-monthly or monthly invoicing cycles with certain customers automatically. You might agree with a customer to invoice them monthly for all orders delivered in that month.
• Internal usage: If our billing system supports it, using summary invoices for repeat customers can be efficient. We should ensure that the VAT on each delivery is still accounted correctly. Many systems will internally treat each delivery note as generating “pro forma” and then consolidate.
• Caveats: Summary invoicing is only between the same supplier and customer. You can’t mix different customers. And if any of the supplies have a different nature that requires separate handling (different currency, or one is intra-EU and others domestic, etc.), you might need separate invoices. Also, if a customer needs an invoice sooner (maybe they want to book costs weekly), they might not want to wait for a monthly summary – in that case, we’d invoice each time.

• Self-billing lets the customer handle invoicing, but requires agreement and vigilance.
• Simplified invoices ease requirements for small sales, but aren’t for mainstream B2B invoices.
• Summary invoices streamline multiple transactions into one, which can simplify our and our customer’s administration.