Accountant for Seafarers and Yacht Crew: Sorting Your Situation First

Crew tend to arrive with the same question and three completely different situations behind it. A deckhand on a privately owned motor yacht out of Antibes, an engineer on a Liberian-flagged product tanker, and a self-employed refit specialist who invoices four different yards in a season are not in the same tax position, and only one of them is usually well served by the advice that circulates in crew mess rooms. Sorting which of the three you are is the first useful thing an accountant does for you, because it decides everything after it.

Three crew situations, and where each one lands

Employed superyacht crew. You are on a contract with a vessel or its management company, you have a rank and a rotation, and you are paid a wage. If you are UK resident, that wage is taxable UK income whether or not it arrives gross from an offshore payroll. Your route is a Self Assessment return each year that reports the employment income and carries any seafaring claim. The 100% deduction from seafarer employment earnings requires an eligible period of at least 365 days made up mainly of days spent outside the UK, and it is available to employees only. The rules that decide whether your period qualifies are set out on our page on how the Seafarers Earnings Deduction works, which walks the qualifying tests in order.

Foreign-flag merchant crew. Your income tax position works the same way as any other UK-resident employee's: residence, not the flag, drives the income tax question. Where the flag genuinely matters is National Insurance, which for mariners runs on its own set of rules. Those two questions get answered separately, by different rules, and getting a clear income tax answer tells you nothing about the National Insurance answer. Your route is the same annual return plus a specific mariners National Insurance check for your ship and employer.

Self-employed marine contractor. If you engage on your own account, invoice several customers, carry your own kit and take the risk on the job, you are a sole trader who happens to work on boats. The seafaring deduction is not yours, because it is an employee-only relief, and no amount of time offshore changes that. This is the situation most often mishandled, because the crew-facing advice online is built around a claim you cannot make. Your route is ordinary self-employment: profit computation, allowable expenses, Class 4 National Insurance, payments on account and a VAT threshold to watch. The rest of this page covers what that looks like in figures.

What a marine accountant does across a tax year

Strip out the marketing and the work is short. For employed crew it is establishing which tax years you need to file for, reconstructing your movements from voyage records, discharge book entries and travel documents, putting the employment income and any claim into the right boxes, filing by 31 January, and answering HMRC if a query comes back two years later. For a self-employed contractor it is bookkeeping through the year, a profit computation at the year end, capital allowances on tools and equipment, the National Insurance calculation, payments on account, and a running eye on turnover against the VAT threshold.

What it is not: a refund operation. If you are quoted a percentage of a repayment, asked to sign a nomination or assignment so that money from HMRC lands somewhere other than your own bank account, or funnelled through a free qualifying test before anyone will speak to you, you have found a different kind of business. Claims that belong on your return go on your return, and the money comes to you.

Do you need to file a UK tax return as crew?

If you are UK resident with seafaring income, in nearly every case yes. Most of the trouble comes from a pair of beliefs that sound sensible and are wrong. The first is that a foreign employer's gross payment means the income is untaxed by design; it means nobody has collected anything yet, and a foreign employer with no UK presence simply sits outside PAYE, which moves the whole reporting obligation onto you. The second is that a seafaring claim replaces the return. It does not. The claim is made on the return, so the return has to exist first, even in a year where the claim reduces the liability to nothing.

The deadlines are the ordinary ones. Register for Self Assessment by the 5 October following the end of the tax year in which the liability arose, file online by the following 31 January, and pay by the same date. Missing a filing deadline is charged whether or not tax is owed, which catches out crew whose claim covers the liability entirely.

Ship tax: what tonnage tax is, and what it is not

Tonnage tax is an elective ring-fenced corporation tax regime for ship-operating companies. A qualifying company can elect into it, and its shipping profits are then computed by reference to the net tonnage of the ships it operates rather than by the ordinary corporation tax rules. It is a company-level regime, and the ordinary corporation tax computation continues to apply to anything outside the ring fence.

What it means for you on board is nothing. It does not change the rate you pay, the deductions available to you, or whether you file. Operator-level tonnage tax advisory is out of scope for us, and a shipowner or manager weighing an election needs a specialist shipping tax adviser rather than a generalist practice. We state the boundary plainly because "ship tax" is a query crew and owners both type and the two of them need entirely different people.

Self-employed at sea: the numbers that decide your year

A self-employed marine contractor is taxed on profit, meaning income from your engagements less the expenses you incurred wholly and exclusively for the work. Typical deductible costs are your own tools and safety kit, certification and professional subscriptions related to the work, travel to and from a vessel you are not employed on, insurance and the cost of running your admin. Equipment with a life beyond the year goes through capital allowances rather than straight into expenses.

For 2026/27 the personal allowance is £12,570 and the basic rate is 20% up to £50,270, with 40% above that to £125,140 and 45% beyond. Class 4 National Insurance runs at 6% on profits between £12,570 and £50,270 and 2% above. Those bands and the 6% Class 4 rate are locked in our figures for 2025/26 and were still current when this page was checked in August 2026, so confirm them against the current year's rates before you rely on them for a later year. Scotland sets its own income tax bands, which changes the income tax lines below but not the National Insurance ones. Class 2 National Insurance stopped being payable from 6 April 2024 for profits at or above the Small Profits Threshold, so a contractor at these profit levels does not pay a weekly charge.

Worked example: a refit contractor's 2026/27 bill

Otis takes short engineering contracts on yachts refitting in and around Falmouth, invoicing four different yards across the year. He is self-employed, not on anyone's articles, so no seafaring deduction is in play.

Line	Amount	How it is arrived at
Invoiced income	£58,400	Total billed across four yards in 2026/27
Allowable expenses	£12,400	Tools, safety kit, insurance, travel to vessels, certification, admin
Taxable profit	£46,000	£58,400 less £12,400
Income taxed at 20%	£33,430	£46,000 less the £12,570 personal allowance
Income tax	£6,686.00	£33,430 at 20%
Class 4 National Insurance	£2,005.80	£33,430 at 6%, all of it below the £50,270 upper limit
Total due	£8,691.80	£6,686.00 plus £2,005.80

The cash flow is the part that surprises people in a first year. Because the total exceeds £1,000, Otis also makes payments on account towards the following year, each 50% of this year's liability, so £4,345.90 falls due on 31 January and the same again on 31 July. His January payment is therefore £8,691.80 for 2026/27 plus £4,345.90 on account, £13,037.70 in one go. Set that money aside monthly or the first January will be memorable for the wrong reason.

Change one figure and the whole table moves, which is the point of showing it this way. If Otis had bought a £6,000 machine and claimed the full cost as a capital allowance, profit would be £40,000, the taxed slice £27,430, income tax £5,486.00 and Class 4 £1,645.80.

VAT once the invoices add up

Registration becomes compulsory when taxable turnover passes £90,000 in any rolling twelve months, or when you expect to pass it within the next thirty days. Below that you may register voluntarily to recover input VAT, which occasionally suits a contractor buying substantial equipment. The deregistration threshold is £88,000. Rolling twelve months means exactly that: a busy refit season can push you over on a period that straddles two tax years, so check the running total monthly rather than at the year end.

Marine work also raises place of supply questions, because the answer can depend on where your customer belongs and where the vessel is. Two contractors with identical turnover can have different registration positions for that reason. If you are within sight of £90,000 and most of your customers are overseas, get the liability of your specific supplies looked at before you register rather than after.

The flag decides your National Insurance, not your income tax

Mariners have a separate National Insurance regime with its own rules, and the flag of your ship is one of the things that drives it. Employed crew, foreign-flag crew and contractors can all land in different places under those rules, and we do not assert an outcome for any flag or employer combination on a page, because the answer genuinely depends on the specific facts of your engagement.

What we do say is that this question gets asked separately and answered separately. Whether or not a claim reduces your income tax to nothing tells you nothing about your National Insurance position, and the contributions record you build now is what supports a state pension later. If nobody has ever looked at the National Insurance side of your arrangement, that is the gap worth closing first.

Choosing someone

Ask how many seafaring returns the firm filed in the last season and what evidence it will ask you for. A firm that immediately names discharge books, voyage records and travel documents has done this before. A firm that leads with a free qualifying test and a percentage fee is running an acquisition funnel. Ask what happens if HMRC opens an enquiry two years later and whether that is inside the fee. Ask, if you are self-employed, whether the quote covers bookkeeping or assumes you deliver clean figures.

Location is irrelevant. Nobody needs to be in a marina town to read a discharge book, and crew are rarely in the same country as their accountant anyway. What matters is whether the work is being done from your actual records, and whether the person doing it will still be there when a letter arrives. If you want to start with the general mechanics of the return itself, our Self Assessment page covers registration, deadlines and what a return costs.