How do you work out your qualifying period of sea time?
Count only full days spent outside UK territorial waters - this is crucial. The number of days you are absent from the UK at midnight is crucial for eligibility. Include travel days to and from the vessel in your calculations.
Sick leave and shore leave abroad count as qualifying time too. Days spent on holiday abroad, as well as return visits, can count towards your qualifying period, provided you are outside of the UK at midnight on those days. However, UK port days and home leave don’t qualify - keep these separate.
Keep detailed records of all movements and dates from day one. Furthermore, use official ship logs to verify your time at sea for HMRC. There is no statutory limit on how many days holiday can be included, as long as the days are spent abroad.
You must also ensure that you complete at least one part voyage to or from a foreign port during each tax year. The half day rule and spending more than half of your time outside the UK are important for qualifying.
One chief engineer I know kept a simple diary throughout his contract. He noted every port, every departure, and every arrival - it made his tax return much easier. Recording each particular day spent outside the UK helps meet HMRC requirements.
