You qualify for Seafarers’ Earnings Deduction if you are an employee working on a ship, you are UK or EEA resident, and you have an eligible period of at least 365 days spent mainly outside the UK. Four conditions, and all four have to be met.
The eligible period, in plain English
This is the condition that decides most claims, and it is widely misdescribed as “183 days out of the country”. It is more precise than that.
An eligible period is a run of at least 365 days made up of days outside the UK and the visits home in between. A visit to the UK can be included in the period only if it passes two tests:
- The 183-day test. No single return visit to the UK lasts more than 183 consecutive days.
- The half-day rule. At the end of that visit’s following trip abroad, your total days in the UK are not more than half of the total days since the period began.
The half-day rule is tested again after every return visit, not once at the end of the year. A period can run for years if you keep passing it. Fail it once, and the period ends and a new one has to be built from scratch.
Days are counted at midnight. You are outside the UK on a given day if you are outside the UK at midnight at the end of it. Days that are not working days still count as days abroad if you were abroad.
A worked example
| Period | Days | Running UK days | Running total | Half-day rule |
|---|---|---|---|---|
| At sea | 120 | 0 | 120 | — |
| Leave in UK | 60 | 60 | 180 | — |
| At sea | 110 | 60 | 290 | 60 of 290 — pass |
| Leave in UK | 70 | 130 | 360 | — |
| At sea | 100 | 130 | 460 | 130 of 460 — pass |
That seafarer has an eligible period of 460 days and counting. Now change the second leave to 190 days: it breaks the 183-day test, the period ends, and the clock restarts on the next day abroad.
The voyage condition
Days abroad are only half of it. Your duties count as performed outside the UK when the ship is on a voyage, or part of a voyage, that begins or ends outside the UK. Coastal work between UK ports, and work in the UK sector of the North Sea, is treated as work in the UK.
Who cannot claim
- Crown employees — Royal Navy personnel cannot claim. Royal Fleet Auxiliary employees can, despite being Crown employees.
- Workers on offshore installations — rigs, platforms, FPSOs, drillships, flotels. See offshore workers and SED.
- The self-employed — SED is a deduction from employment income.
- Residents of countries outside the UK and EEA.
Common questions
Do I need to be out of the UK for 183 days in the tax year?
No, and this trips people up. The test is not tied to the tax year. It is an eligible period of at least 365 days that can start and end on any date, provided the 183-day and half-day rules are met throughout.
I spent 184 days at home after an injury. Have I lost everything?
That visit breaks the period, so earnings after it need a new eligible period. Earnings in the period before it are not affected.
Do I qualify if I also have a job ashore?
SED applies to your earnings as a seafarer. Other income is taxed normally, and time ashore in the UK counts as UK days.
Does a holiday abroad count as days out of the UK?
Yes. Non-working days spent outside the UK can be counted.
Not sure where you stand?
Tell us your vessel, your dates and where you sailed. We will tell you plainly whether you have a claim.
Related: How to claim SED · Cruise ship crew · Backdating a claim
Based on HMRC Helpsheet HS205, Seafarers’ Earnings Deduction. Tax rules change and individual circumstances differ — this page is general information, not advice on your own position.
