If you imported any non-controlled goods from the EU into Great Britain from 1 January 2021, you (or the customs intermediary that advises you) may have decided to use delayed declarations instead of declaring your goods to HMRC at the time you imported them.
If you did choose to delay, then you need to make your supplementary declarations within 175 days.
The first supplementary declarations are due from 25 June 2021, so if you imported anything in January (and you have not yet made your supplementary declaration), you only have a few weeks left to prepare.
Source HMRC
