Seafarer's Tax Days Calculator

When filing your HMRC income tax return under the Seafarers Earnings Deduction, you are required to complete the Self Assessment Helpsheet HS205. This form is designed to enable you to detail all of your departures and returns to the UK, and calculate your initial qualifying period*.

This form is a vital part of your claim and must be retained as evidence as part of your self-assessment submission.

Most seafarers will agree that it is a lengthy and time-consuming task, involving printing and manually completing the form. This is why we have created our easy-to-use online tax days calculator which takes the hard work out of calculating your days at sea.

Use the calculator below by entering the dates you left and returned to the UK. Simply add a row for each individual period you spent offshore.

Once you've added all your dates, our system will display an instant number of days you spent outside the country. The total will tell you whether you have accumulated enough days to qualify under the SED or otherwise.

Calculate Your Tax Days

Enter your leaving and return dates below to calculate how many days you have been outside of the UK within the last year.

Add a new row for each individual period, making sure you click the 'Add dates' button for each entry (see screenshot below):

Add more dates
You have spent 0 days outside of the country

*Initial Qualifying Period

In order to establish a qualifying period for the Seafarers Earnings Deduction (SED), you will need to establish an initial period of 365 days in which you spend less than 183 days in the UK.

Your day count will begin from the first day you set foot upon a vessel and based upon a rolling 365 day period rather than a tax or calendar year.

In order to finalise and confirm this initial period, you must also be outside the UK at midnight on the 365th day following your first day onboard.

Half Day Rule

Once your initial 365 day qualifying period has been established as above, HMRC will view your qualification as an extended period.

As long as you have spent less than half your time in the UK over the period since you first began a claim, and you do not spend 183 consecutive days in the UK, your claim will continue to be valid.

Need Some help?

Do you need some help using our tax days calculator? Or perhaps you've calculated your tax days and would like some assistance filing your self-assessment tax return?

Our professional team of accountants and tax experts are ready to answer your questions.

Call us today on +44 7872 812765 or contact us via email and we'll be happy to help.