Supplementary Declarations (SDs) can be submitted directly by authorised importers themselves or by agents or freight forwarders on the importer's behalf. However, you must be aware of the relevant responsibilities if you use third parties to submit declarations for your goods.
If you submit your own declarations, it's referred to as self-representation, and you'll be responsible for all filing and payment of customs duty and tax.
If you use an agent or a freight forwarder, you must be sure whether they're submitting your declarations under direct or indirect representation. Direct representation means that you as the importer are still liable for any duty and taxes owed to customs. Indirect representation means that you and the agent or freight forwarder are jointly liable for any duty and taxes owed.
If you use a third party purely to process declarations, such as a computer service bureau, they're usually working under direct representation which means you're fully liable.
It's not necessary to complete an individual SD for every transaction.
You can instead use aggregation to combine SDs containing the same header and item level data into a single customs declaration and so reduce the number of SDs you would otherwise have to create. For more information on how to reduce SD completion, see Notice 760.
Managing problems with SDs
If you have problems with SDs, such as errors and omissions or late submissions, it's essential that they're corrected as soon as possible. If you realise you have made an error within 24 hours of submission, you may be able to cancel or amend the SD via the Customs Handling of Import and Export Freight system. If it's later than that, you must contact the HMRC Customs Freight Simplified Procedures (CFSP) National Assurance Team (CNAT) via email at CFSP_cope@hmrc.gov.uk.
You must also advise CNAT immediately if you're unable to submit your SD in time to meet the deadline. Further information about when and how to contact CNAT is available in CFSP Information Paper 66.