Claiming the Seafarers' Earnings Deduction?
Know exactly where you stand with your SED claim.
SED eligibility tracking with plain-English explanations and HS205 export. Free to start.
Available on iOS and Android.
Tracking qualifying days shouldn't be this hard.
If you claim the Seafarers' Earnings Deduction, you've probably been there. Counting days on a spreadsheet. Trying to work out if that extra week ashore broke your qualifying period. Handing everything to an accountant in April and hoping for the best.
Get it wrong and you lose the claim - and the 100% tax back that comes with it.
Most SED apps just give you a yes or a no. SeaClaim shows the detail you need to keep your claim on track.
See why, not just whether
Half-day rule breach. 183-day limit exceeded. No foreign port in a tax year. Every result tells you which rule was broken and how far short you were.
Plan your time ashore
45 days in hand. Fail date: 8 July. 20 out of 183 UK days used. That's your dashboard. Check it before you book shore leave, before you sign a contract.
An algorithm you can verify
SeaClaim implements the full HMRC HS205 working sheet methodology. You can see the complete breakdown for every qualifying period - which voyages counted, which tax years are claimable, and why. If you want to check the result against HMRC's guidance yourself, everything is there.
The hardest part of your SED claim, done
Generate a completed HS205 working sheet PDF - columns A through H - ready for your Self Assessment or your accountant. Arrive with the complex bit already handled.
File your Self Assessment yourself
The in-app guide walks you through the HMRC forms step by step. Which boxes to fill in, what to enter, how to claim the Seafarers' Earnings Deduction on your return. A tax refund calculator shows you what you're getting back before you file.
Most seafarers pay an accountant £300-400/year for SED work.
SeaClaim Pro is £9.99/year and covers the full process.
How seafarers handle SED today
| Spreadsheet | Accountant | SeaClaim | |
|---|---|---|---|
| Tracks qualifying days | Manual | They do it | Automatic |
| Explains why you qualify | No | If you ask | Every result |
| Live risk metrics | No | No | Days in hand, fail date |
| HS205 working sheet | No | They produce it | PDF export |
| Available on your phone | No | No | Yes |
| Self Assessment guidance | No | They file it | Step-by-step guide |
| Annual cost | Free | £300-400 | Free / £9.99 |
Start free. Upgrade when you need to.
Free
- Up to 10 voyage entries
- Full eligibility tracking
- Plain-English status explanations
Pro
£9.99/year
- Unlimited voyages
- Risk metrics (days in hand, fail date, 183-day tracking)
- Smart notifications before you breach a rule
- HS205 working sheet PDF export
- Step-by-step Self Assessment guide
- Tax refund calculator
- CSV data export
Stop guessing. Start tracking.
SeaClaim gives you clear eligibility explanations, live risk metrics, and a completed HS205 working sheet - built on the full HMRC methodology.
- Plain-English explanations for every eligibility result
- Days in hand, fail date, and 183-day tracking on your dashboard
- HS205 PDF export ready for Self Assessment or your accountant
- Step-by-step Self Assessment guide with tax refund calculator
- Free to start. Pro for £9.99/year.
Available on iOS and Android.
Common questions about SED and SeaClaim
What is the Seafarers' Earnings Deduction?
The Seafarers' Earnings Deduction (SED) is an HMRC deduction that can reduce the income tax on your seafaring earnings to zero. To qualify, you need to work on a ship, build up an eligible period of at least 365 days outside the UK, and have at least one voyage that begins or ends at a foreign port. Read our full SED guide for a detailed breakdown of the rules.
Is SeaClaim a seafarer tax calculator?
It's getting there. SeaClaim tracks your eligibility for the Seafarers' Earnings Deduction, shows you which rules are in play, and produces the HS205 working sheet you need for your claim. The in-app Self Assessment guide walks you through the HMRC forms step by step, and a tax refund calculator shows you what you're claiming back.
What is the HS205 working sheet?
The HS205 is the official HMRC form used to calculate your eligible period for SED. It tracks your departures and returns, counts UK days, checks the half-day rule, and determines which tax years are claimable. SeaClaim implements the full HS205 methodology and can export a completed working sheet as a PDF.
How do qualifying days work for SED?
A qualifying day is any day where you're outside the UK at midnight. The day you depart counts as abroad; the day you return does not. You need to string together enough qualifying days to build an eligible period of at least 365 days, without breaching the half-day rule or the 183-day UK visit limit along the way.
How many days can I spend in the UK and still claim SED?
Two limits apply. First, no single UK visit can exceed 183 consecutive days. Second, your total UK days must never exceed half the total days in your eligible period so far (the half-day rule). Breach either one and your eligible period ends on the previous return date. SeaClaim's dashboard tracks both of these live.
What is the half-day rule?
After each return to the UK, HMRC checks whether your total UK days exceed half the days in your eligible period so far. If they do, your period ends on the previous return date and you have to start again. It's the rule most likely to catch people out, especially after a longer stretch ashore. SeaClaim shows you exactly how close you are to breaching it. More on the key rules.
Do holidays abroad count towards my qualifying days?
Yes. Any day you're outside the UK at midnight counts as a qualifying day, whether you're working or on holiday. The Channel Islands, Isle of Man, and Republic of Ireland all count as abroad for SED purposes. Keep travel evidence - boarding passes, receipts, bank statements - as HMRC can ask for proof.
Do I need an accountant to claim SED?
Not necessarily. SeaClaim handles qualifying day tracking, HS205 generation, and now includes a step-by-step Self Assessment guide that walks you through the HMRC forms for claiming SED. You'll still need your own earnings evidence and voyage documentation, but the complex parts - the calculations, the working sheet, and knowing which boxes to fill in - are covered.
Is SeaClaim free?
The free tier gives you up to 10 voyage entries with full eligibility tracking and plain-English explanations. SeaClaim Pro is £9.99/year and adds unlimited voyages, risk metrics (days in hand, fail date, 183-day tracking), smart notifications, and HS205 PDF export.
Does SeaClaim replace my accountant?
For the SED part of your tax return, it can. SeaClaim handles qualifying day tracking, HS205 generation, and now includes a step-by-step Self Assessment guide with a tax refund calculator. You'll still need to gather your own earnings evidence and voyage documentation, but the process of working out your eligibility, producing the HS205, and filing the claim is covered. That's the £300-400/year an accountant typically charges for SED work.