UK Late Filing Penalty Calculator

A £100 fixed penalty applies the moment the deadline passes, even if you owe no tax at all. From three months late HMRC can charge £10 a day for up to 90 days (a further £900). At six months and again at twelve months a tax-geared penalty is added, each the greater of 5% of the tax due or £300. Late filing and late payment are separate penalty regimes and both can run at once.

Yes. The initial £100 late filing penalty is fixed and is not reduced because your liability is nil or because you are due a refund. It applies simply because a return that was required was not delivered on time. The later tax-geared penalties at six and twelve months are the greater of a percentage of the tax due or £300, so a nil liability still attracts the £300 floor.

For a tax year ending 5 April, the paper filing deadline is the following 31 October and the online filing deadline is 31 January. The balancing payment is also due by 31 January, with payments on account due 31 January and 31 July. You must notify HMRC of chargeability by 5 October following the end of the tax year if you are not already in Self Assessment.

Once a return is three months late, HMRC may charge £10 for each day it remains outstanding, for a maximum of 90 days — a further £900 on top of the initial £100. HMRC must give notice that daily penalties are being charged and specify the date from which they run. They stop once the return is filed or once 90 days have elapsed, whichever comes first.

At six months a penalty of the greater of 5% of the tax due or £300 is charged. At twelve months a further penalty applies on the same basis for ordinary cases. Where HMRC concludes information was withheld deliberately the twelve-month penalty rises sharply — broadly up to 70% of the tax due for deliberate withholding and up to 100% where it was deliberate and concealed.

Yes, and this catches people out. Filing penalties punish the missing return; late payment penalties punish the unpaid tax. If you file late and pay late you can be charged under both regimes for the same year, plus interest on the unpaid tax. Filing on time while you arrange to pay at least stops the filing penalties accruing.

For Self Assessment balancing payments, a 5% penalty applies to tax still unpaid 30 days after the due date, a further 5% at six months, and another 5% at twelve months. These are charged on the amount outstanding at each of those points, so paying something down before each trigger date reduces the penalty that follows.

Yes. Interest runs on tax paid late from the due date until payment, and it is charged in addition to any penalties — it is not a penalty itself and is not usually reduced on appeal. Interest is also charged on unpaid penalties. Because it accrues daily, the cost of delay keeps rising even after the twelve-month penalty points have passed.

The ordinary assessment window is four years from the end of the tax year. It extends to six years where the loss of tax was brought about carelessly and twenty years where it was deliberate. A separate twelve-year window applies to assessments involving an offshore matter, regardless of whether the taxpayer took reasonable care, subject to a carve-out where HMRC already held information enabling it to assess in time.

The UK penalties are the same, but the exposure is usually larger because the untaxed income sits abroad. HMRC treats offshore non-compliance more severely through the territory categories, and the twelve-year assessment window commonly applies. You may also have a parallel US filing problem for the same years, so the two disclosures need sequencing rather than being handled in isolation.

You can appeal if you have a reasonable excuse for the failure and you put matters right without unreasonable delay once the excuse ends. HMRC generally accepts serious illness, bereavement, a genuine postal or service failure, or an unexpected event outside your control. Pressure of work, lack of funds, and reliance on someone else to file are not usually accepted on their own.

HMRC looks for something unusual and outside your control that stopped you filing on time — for example a serious or life-threatening illness, the death of a close relative shortly before the deadline, a documented failure of HMRC's own online service, or a fire, flood or theft affecting your records. The excuse must have persisted throughout the period of default and you must file promptly afterwards.

It usually does. Penalties for the behaviour underlying a disclosure are reduced according to the quality of the disclosure — telling, helping and giving access to records — and unprompted disclosures attract a materially lower range than prompted ones. Coming forward before HMRC contacts you is the single most effective step available to reduce a penalty.

Where a return is not filed, HMRC can issue a determination of the tax due. A determination carries no right of appeal and can only be displaced by filing the actual return, generally within three years of the filing date, or twelve months from the determination if that is later. Enforcement action continues in the meantime, so the return remains the only route out.

It applies the fixed £100 penalty, the £10 daily charge from three months (capped at 90 days), the tax-geared penalties at six and twelve months, the 5% late payment penalties at 30 days, six months and twelve months, and simple interest on the tax outstanding at the rate you enter. It is an estimate for orientation only and does not model reductions for disclosure quality, suspension, or special reduction.