Check the basic HMRC eligible-period day test and estimate the seafaring earnings that may qualify for deduction.
Estimate your Seafarers’ Earnings Deduction
e.g. date you left the UK to begin the period.
e.g. date you returned or the period ends.
Other duties must normally be incidental to the ship duties.
Enter 0 if none.
| At least 365 days | |
|---|---|
| At least half the days absent from the UK | |
| No continuous UK stay over 183 days | |
| Ship duties and qualifying voyage answers |
Passing these basic checks does not confirm legal eligibility. Use HMRC’s HS205 working sheet and keep supporting records.
What is the Seafarers’ Earnings Deduction?
The Seafarers’ Earnings Deduction can allow qualifying seafarers to deduct eligible employment earnings when calculating UK Income Tax. It applies to qualifying ship-based employment and eligible periods, not automatically to every offshore worker or every day spent outside the UK.
HMRC’s current Seafarers’ Earnings Deduction HS205 guidance explains the detailed conditions and includes the official working sheet.
How the calculator checks the eligible period
An eligible period normally lasts at least 365 days. For a combined period containing days abroad and days in the UK, at least half of the days must be days of absence from the UK. A continuous stay in the UK of more than 183 days can break the combined-period test.
HMRC normally decides whether a person was absent from the UK by their location at midnight. Real HS205 calculations can involve several voyages and visits, so the simple totals entered here cannot replace a dated travel log.
How the estimated deduction is calculated
If all basic checks pass, the calculator starts with entered seafaring employment earnings and subtracts non-seafarer or offshore-installation earnings plus entered pension contributions, allowable expenses and capital allowances. The result is an indicative deduction amount.
| Entered amount | Calculator treatment |
|---|---|
| Seafaring employment earnings | Starting amount for the estimate |
| Non-seafarer duties or offshore-installation earnings | Excluded from the estimate |
| Registered pension contributions and allowable deductions | Subtracted before displaying the estimated deduction |
Worked example
A period of 400 days with 230 days absent from the UK passes the 365-day test and the half-days test. If the longest continuous UK stay is 45 days and the ship-duty answers are both yes, entered earnings of £52,000 less £2,000 of excluded duties and £1,500 of adjustments produce an indicative deduction of £48,500.
Who may qualify?
HMRC states that the deduction is available to qualifying UK-resident employees and certain non-UK residents who live in an EU or EEA state. Duties must be performed wholly or mainly on a ship, with other duties normally incidental, and earnings must arise in the eligible period. Work on offshore installations is treated differently.
The location of duties also matters. HMRC generally regards seafarer duties as performed outside the UK when they are carried out on a vessel engaged on a voyage, or part of a voyage, that begins or ends outside the UK.
Records and claiming
Keep discharge books, passports, travel records, freeboard logs, contracts, payslips and details of the ships on which duties were carried out. UK residents normally claim through Self Assessment, using the Additional Information pages and HS205. The amount entered in the claim should follow the official working sheet, not only this estimate.
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Frequently asked questions
How long must the eligible period be?
It must normally consist of at least 365 days.
How many days must be spent outside the UK?
For a combined eligible period, at least half of the days must be days of absence from the UK.
Can I stay in the UK during the eligible period?
Yes, a combined period can contain UK days, but the absence ratio must still pass and a continuous UK stay exceeding 183 days can break the test.
Does offshore-platform work qualify?
Not automatically. HS205 covers employment on ships and excludes earnings from duties on offshore installations from the deduction calculation.
Does passing this calculator guarantee the deduction?
No. It checks only basic inputs. HMRC’s HS205 working sheet and the full employment, voyage and residence facts determine the claim.