Everything you need to know
about SED compliance.

What is Seafarers' Earnings Deduction (SED)?

A complete beginner's guide to SED — who qualifies, what it means for your tax bill, and why it matters.

How the Half-Day Rule works

HMRC determines UK days by where you are at midnight. Here's exactly how the rule works and how easySED applies it automatically.

The 182-Day Rule explained

You must spend more than half the qualifying period outside the UK. Here's how the 182-day threshold is calculated and what breaks it.

How to file a provisional SED claim

Mid-year when the tax year ends before your 365 days are up? Here's how to file provisionally and protect your entitlement.

What evidence does HMRC actually want?

Discharge books, payslips, contracts — a practical list of what you need to keep and how to organise it for a smooth claim.

5 mistakes that cost seafarers their SED claim

Missing a midnight rule, losing evidence, UK days creeping over the limit — the most common errors and how to avoid every one.