Self Assessment for holiday let owners: the deadlines, and what late costs

The tax on a British holiday let is rarely what stings. What stings is the calendar around it: a registration deadline in October that most owners have never heard of, a filing deadline in January, a second payment deadline in July, and a penalty structure that keeps charging long after the return has been filed. None of it is difficult. All of it is date-driven, which means it is the kind of problem that is solved in a diary rather than in a spreadsheet.

The first deadline is not the return, it is telling HMRC

If you have not sent a tax return before, or you registered previously but did not need to send one for the 2024 to 2025 tax year, you must tell HMRC by 5 October that you need to complete a return for the previous year. The tax year in question started on 6 April 2025 and ended on 5 April 2026. You tell them by registering for Self Assessment.

Miss it and the machine does not simply move on. Register after 5 October 2026 and HMRC will write or email with a different filing deadline, three months from the date on that letter or email. The tax itself is not rescheduled: it is still due by 11.59pm on 31 January 2027. And if you register late and do not pay the whole bill by 31 January, you may get a failure to notify penalty, calculated on the amount still outstanding and issued within twelve months of HMRC receiving the return.

This catches first-year owners with reliable regularity. The cottage completed in the spring, the first bookings ran through the summer, and the owner assumed the paperwork started in January. It started in October.

The four dates that matter afterwards

• 31 October 2026 - HMRC must receive a paper return by 11.59pm, or a late filing penalty follows.
• 30 December 2026 - the cut-off for submitting online if you want the bill collected through your tax code. Miss it and you pay another way.
• 31 January 2027 - the online return and the tax itself, both by 11.59pm.
• 31 July - the second instalment, if you make payments towards your bill through payments on account.

Two of those are quietly useful. The tax-code route spreads a modest liability across a salary without a separate payment, which suits an owner with employment income and one property. And a return can be submitted at any time from 6 April onwards, which means the bill is knowable nine months before it is payable. HMRC publishes a calculator to estimate the bill before the return is sent, precisely so that the money can be set aside rather than found.

The penalties, in the order they arrive

HMRC's 2026 late-filing schedule is one that owners underestimate because they focus on the first number:

• an initial £100 penalty;
• after three months, daily penalties of £10 per day, up to £900;
• after six months, a further 5% of the tax due or £300, whichever is greater;
• after twelve months, another 5% or £300, whichever is greater.

Read that 2026 list twice and the shape of it becomes clear. The £100 is the smallest part. A return abandoned for a year has collected the initial penalty, up to £900 of daily charges, and two percentage-based charges, before a single pound of the actual tax has been paid.

Late payment is charged separately, and the two stack. In 2026, penalties of 5% of the tax unpaid apply at 30 days, at six months and at twelve months, with interest on the amount owed on top. Filing on time and paying late still costs money; so does paying on time and filing late.

Partnerships deserve a line of their own, because joint ownership structures sometimes drift into one. Where a partnership return is late, all partners are charged a penalty, not only the one who was supposed to file it.

If a penalty lands

A penalty must be paid within 30 days of the date on the penalty notice. If you have a reasonable excuse, you can appeal. HMRC also publishes a tool to estimate penalties for late returns and late payments, which is worth running before assuming the worst, and again before assuming the best.

The practical advice is unglamorous: if the return is going to be late anyway, send it as soon as possible rather than waiting until the figures are perfect. The daily charges stop when the return arrives, not when it is accurate to the pound, and an estimated figure corrected later costs less than a perfect figure filed in April.

What we ask owners to put in the diary

Three entries cover most of it. An entry in September, to check whether a first-year property triggers the 5 October notification. An entry in late April, to send the return early and learn the number while there is still time to plan for it. An entry in mid-July, for the payment on account that surprises owners in their second year far more often than the first bill did in their first.

Changes are coming to how property income is reported digitally, and they run on their own timetable rather than this one. For the current cycle, these are the dates that govern. We study every request and tell you honestly whether and how we can help.