Here’s the quiet advantage many crew miss: if your salary qualifies for the Seafarer’s Earnings Deduction and you have no other UK income, your personal allowance is sitting there unused.
The maths
Rental profit up to the personal allowance can be entirely tax-free. On a typical single buy-to-let, that can mean no UK tax at all on the rental income — legitimately, and with a filed return to prove it.
The catch
You must still file. The allowance is applied through your self-assessment return, and skipping the return is what triggers penalties — not the tax itself.