The liability to register under GST arises when aggregate turnover of a supplier exceeds threshold limits. The registered person acquires a 15-digit GSTIN from the tax authorities so that he is eligible to collect tax on behalf of the Government and thereby avail the benefit of Input Tax Credit.
Every registered person shall make a self-assessment of his output GST payable and furnish the same in his respective monthly / annual return after discharging the computed liability. Self Assessment under GST can be availed by every taxable person registered under the provisions of GST law, now the question arises whether an unregistered person can also opt for Self Assessment and pay tax
Source Taxguru
