UK Tonnage Tax Calculator

UK tonnage tax is an alternative to corporation tax for qualifying shipping companies. Instead of calculating tax on actual shipping profits, the company pays CT on a 'deemed' profit based on the net tonnage of each vessel in its fleet and the number of days it was operated.

The deemed daily profit is: £0.60 per 100 net tonnes for the first 1,000 NT; £0.45 per 100 NT for 1,001–10,000 NT; £0.30 per 100 NT for 10,001–25,000 NT; and £0.15 per 100 NT for tonnage above 25,000 NT. This is multiplied by the number of days each vessel is operated in the regime.

Net tonnage (NT) is the internationally standardised measure of a ship's usable cargo/passenger capacity, calculated under the International Convention on Tonnage Measurement. It is determined at registration and shown on the ship's certificate of registry.

To enter the UK tonnage tax regime, a company must: be resident in the UK or have a UK permanent establishment; be engaged in the qualifying trade of operating ships; have strategic and commercial management of ships in the UK; and commit to annual crew training obligations.

Shipping is capital-intensive and cyclical. Tonnage tax provides predictable, low tax bills regardless of actual profit levels. In profitable years, tonnage tax is significantly lower than CT on actual profits. It also provides certainty for long-term investment planning.

Once a company enters tonnage tax, it is locked in for 10 years and cannot revert to standard CT on shipping income. If it leaves before 10 years, HMRC can charge a clawback of any tax advantage gained. The 10-year period runs from the date of entry.

UK tonnage tax covers 'ships' as defined — vessels used for commercial transportation. It generally does not cover offshore construction vessels, drilling rigs, dredgers, or fishing vessels, which have separate tax treatment.

Companies in tonnage tax cannot opt out during the 10-year lock-in period (except in exceptional circumstances approved by HMRC). After 10 years, they can renew for another 10 years or revert to normal CT.

There is a flag condition — a proportion of fleet must be UK-registered (or the company must be working towards this). The government has reformed the flag condition over time to encourage use of the UK Ship Register.

Companies in tonnage tax must commit to minimum officer cadet training levels. The minimum training obligation is to take on one cadet per 15 officers employed or 1 new cadet per year per company (whichever is higher). Failure to meet training obligations results in a training levy.

Yes. Cruise ships operated as part of a qualifying trade are eligible for tonnage tax. The cruise ship's net tonnage determines the deemed profit calculation. Many major cruise lines with UK operations use the tonnage tax regime.

Ships cannot claim capital allowances while in the tonnage tax regime — the deemed profit replaces all profit-based calculations. On exit from tonnage tax, a 'deemed disposal/acquisition' at market value may trigger capital allowance calculations on the ships.