How to Claim SED — Self Assessment, NT Tax Code & Time Limits

Once you've built a valid eligible period, the next step is claiming your deduction. Here's how to do it, how to get an NT tax code so you stop paying tax upfront, and the deadlines you must not miss.

Claiming via Self Assessment

SED is claimed through a Self Assessment tax return. If you're not already registered, you'll need to register with HMRC first. Here's the process:

If you haven't already, register at GOV.UK. Do this as early as possible — HMRC can take time to set up your account and issue your UTR number.

Complete the HS205 working sheet

Use HMRC's HS205 working sheet to calculate your eligible period and the amount of the deduction. Keep this — HMRC may ask to see it.

Complete your tax return

Enter the deduction figure in box 11 of the Additional Information pages of your return. In the "Any other information" box, include the names of the ships you worked on during the year.

Keep your evidence — don't send it

Do not send your supporting documents with the return. Keep them safe — discharge book, travel tickets, payslips, passports — and produce them only if HMRC asks. easySED stores all of this for you.

The NT tax code — stop paying tax upfront

If you're on PAYE, you're probably paying income tax out of every payslip and claiming it back later. An NT (No Tax) code changes that — your employer pays your wages with no tax deducted at source, so you keep more of your money throughout the year.

To qualify for an NT code you must:

Be a UK resident in a PAYE employment
Work on a vessel that qualifies as a ship for SED purposes
File a Self Assessment return every year
Have a contract of at least 12 months — or at least 6 months of continuous employment with the same employer working outside the UK

HMRC won't issue NT until your first claim is processed

You can only apply for an NT code after HMRC has processed your first successful SED claim. Use form R44 to request it. If your circumstances change and you no longer qualify, tell HMRC immediately — any underpaid tax is repaid in one lump sum.

EEA residents — a different process

If you're not a UK resident but are a tax resident of an EEA country, you can't use a standard Self Assessment return. Instead, submit form R43M(SED) — the Repayment Claim for EEA resident merchant seafarers — to reclaim any tax deducted under PAYE.

Records to keep

Don't send these with your return, but hold on to all of them — HMRC can ask to see them at any point:

Completed HS205 working sheet
Seafarer's discharge book
Air tickets and travel vouchers
Passport and visas
Hotel bills and receipts
Freeboard logs of ships worked on

HMRC can contact your employer

HMRC may reach out to your employer directly to verify voyage and crew details. Make sure everything in your return matches your employment records.

Deadlines — don't miss them

You have 4 years from the end of the relevant tax year to make a claim. Miss the window and the claim is gone permanently.

Tax year	Ending	Claim by
2020 to 2021	5 April 2021	5 April 2025
2021 to 2022	5 April 2022	5 April 2026
2022 to 2023	5 April 2023	5 April 2027
2023 to 2024	5 April 2024	5 April 2028
2024 to 2025	5 April 2025	5 April 2029

Disclaimer

easySED is a record-keeping tool, not tax advice. Always consult a qualified tax adviser for guidance specific to your situation.

Build your evidence as you go.

easySED captures everything HMRC needs — discharge book photos, travel records, day counts — automatically, trip by trip.

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How the 365-day eligible period works