What is SED?

Seafarers' Earnings Deduction is a UK tax relief that lets eligible seafarers deduct 100% of their seafaring income from their taxable earnings. In plain terms: you pay no income tax on money earned at sea, as long as you qualify.

It's one of the most valuable tax reliefs available to any group of UK workers. A seafarer earning £50,000 a year who qualifies could save over £10,000 annually.

SED doesn't apply automatically
You still need to file a Self Assessment tax return to claim it each year. easySED builds the evidence trail you need to do that confidently.

Who qualifies?

You must meet all three conditions:

  • You work on a ship. Either all your duties are on a ship, or most are — and any duties off the ship are directly connected to your onboard work.
  • You spend enough time outside the UK. You need a qualifying "eligible period" of at least 365 days, made up mainly of days abroad.
  • You are a UK resident — or a tax resident of an EEA country other than the UK.

Having more than one job doesn't disqualify you — you can claim the deduction against your seafaring income only.

Who cannot claim?

✓ Can claim

  • UK-resident seafarers on a qualifying ship
  • EEA-resident seafarers (non-UK)
  • Royal Fleet Auxiliary employees
  • Seafarers with multiple jobs (seafaring portion only)

✗ Cannot claim

  • Crown employees (e.g. Royal Navy)
  • Non-UK, non-EEA residents
  • Workers on offshore installations
  • Anyone not meeting the 365-day rule

What counts as a ship?

The word "ship" isn't defined in tax law, but HMRC is very clear about what doesn't count. If you work on an offshore installation, your vessel does not qualify — no matter where in the world it is.

Offshore installations that do not qualify include:

  • Fixed and floating production platforms
  • Floating storage units and FPSOs
  • Mobile offshore drilling units — drillships, semi-submersibles, jack-ups
  • Flotels attached to offshore installations
Offshore workers
This exclusion applies even when the installation is moving between locations or temporarily out of use. If the structure exploits mineral resources via a well, it does not qualify.

Your duties count as "outside the UK" if they are carried out on a vessel engaged in a voyage that begins or ends outside the UK. Note: the UK sector of the North Sea counts as UK.

Let easySED track it for you.

Log your movements, capture evidence and know your eligibility status in real time — no spreadsheets needed.

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