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Advanced Taxation (UK) · Appropriateness of planning measures to a taxpayer's circumstances and objectives

Standard Penalties for Errors in Returns for ACCA ATX

Updated 11 October 2026 · Fact-checked

A standard penalty for errors applies when a return or document is inaccurate. The penalty is a percentage of the potential lost revenue. The percentage depends on behaviour: careless, deliberate but not concealed, or deliberate and concealed. Disclosure to HMRC, especially unprompted, lets you reduce the penalty to a minimum percentage.

Understand Standard Penalties for Errors in Returns

When a taxpayer submits an inaccurate return and tax is understated, HMRC can charge a penalty on top of the extra tax and interest. The penalty is a percentage of the potential lost revenue (PLR). This is the extra tax HMRC would have lost if the error had not been found.

The percentage depends on the taxpayer's behaviour. There are three levels. Careless means the taxpayer did not take reasonable care. Deliberate but not concealed means the error was knowingly made but not hidden. Deliberate and concealed means the error was knowingly made and steps were taken to hide it, such as false documents.

The tables you are given show a maximum penalty and two minimum penalties for each behaviour. The minimum depends on disclosure. An unprompted disclosure is made when the taxpayer has no reason to believe HMRC has found or is about to find the error. A prompted disclosure is made after that point. Unprompted disclosure gives a lower minimum.

The actual penalty sits between the minimum and the maximum. HMRC looks at the quality of the disclosure: telling HMRC about the error, helping to quantify it, and allowing access to records. Better disclosure moves the penalty towards the minimum.

In the exam, you are usually told the behaviour and whether disclosure was prompted. You pick the right range, state it, and apply it to the tax underpaid. Always give a range and say where in the range the penalty is likely to fall, with reasons.

Key rules to remember

Penalty amount
Penalty = penalty % × potential lost revenue (PLR)
PLR is the additional tax due because of the error. Work out the tax first, then the penalty.
Careless error
Maximum 30%; minimum 0% (unprompted) or 15% (prompted)
Applies where reasonable care was not taken.
Deliberate but not concealed
Maximum 70%; minimum 20% (unprompted) or 35% (prompted)
The error was knowing but no attempt to hide it.
Deliberate and concealed
Maximum 100%; minimum 30% (unprompted) or 50% (prompted)
The error was knowing and hidden.
Interest on underpaid tax
Interest = underpaid tax × 8.50% × time
Use the rate given in the tax tables (8.50% on underpaid tax). Interest is separate from the penalty.

How to solve Standard Penalties for Errors in Returns questions

Use this method for any question on penalties for errors in returns.

  1. 1Identify the error and work out the extra tax due (the potential lost revenue). Do this first, because every penalty is a percentage of it.
  2. 2Decide the taxpayer's behaviour from the facts: careless, deliberate but not concealed, or deliberate and concealed. Quote the facts that support your choice.
  3. 3Decide whether disclosure is prompted or unprompted. Look for whether HMRC had already started an enquiry or was about to find the error.
  4. 4Pick the correct row in the penalty table and state the maximum and the relevant minimum percentage.
  5. 5Convert the percentages into pounds by multiplying by the PLR. Show both the minimum and maximum penalty.
  6. 6Say where in the range the penalty is likely to fall, based on how helpful and complete the disclosure is.
  7. 7Add any interest on the underpaid tax if asked, and give a short conclusion or advice to the client.

Quickest way: Table lookup and multiply

When to use it: Use this when the question gives the behaviour and the tax underpaid and asks for the penalty range.

  1. Write down the PLR in pounds.
  2. Find the behaviour row in the table provided in the exam.
  3. Circle the right minimum column (unprompted or prompted).
  4. Multiply the PLR by the minimum and maximum percentages.
  5. Write one line justifying the likely position in the range.

Common mistakes in Standard Penalties for Errors in Returns

  • Applying the penalty percentage to the total tax liability instead of the extra tax due to the error.

    Students see the tax figure in the question and use it without checking what is underpaid.

    Fix: Compute the difference between the correct tax and the tax shown on the return. Use only that as PLR.

  • Giving a single penalty figure instead of a range.

    Students think the exam wants one number.

    Fix: Give the minimum and maximum, then explain where the penalty is likely to sit within the range.

  • Treating a disclosure as unprompted when HMRC had already opened an enquiry.

    Students focus on the fact that the taxpayer told HMRC and ignore timing.

    Fix: A disclosure is unprompted only if the taxpayer had no reason to believe HMRC had discovered or was about to discover the error. Check the timeline.

  • Mixing up the minimum percentages for the three behaviours.

    There are nine figures to remember and they look similar.

    Fix: Learn the pattern. Maximums are 30%, 70% and 100%. Minimums rise with seriousness and are lower when unprompted. Always check against the table in the exam.

  • Forgetting interest on the underpaid tax.

    Students concentrate on the penalty and treat it as the full cost.

    Fix: If the question asks for the total cost to the client, add interest at the underpaid rate from the tax table, and keep it separate from the penalty.

Worked examples

Example 1

Priya submitted a tax return which understated her income tax by £8,000 because she did not keep proper records. HMRC found the error during an enquiry. Calculate the range of penalty that could be charged.

Show the solution
  1. PLR = £8,000.
  2. Behaviour: failing to keep proper records points to a lack of reasonable care, so the error is careless.
  3. Disclosure: HMRC found the error, so any disclosure was prompted.
  4. Careless row: maximum 30%, minimum 15% for prompted disclosure.
  5. Minimum penalty = 15% × £8,000 = £1,200.
  6. Maximum penalty = 30% × £8,000 = £2,400.
  7. Her cooperation during the enquiry would move the penalty towards the minimum.

Answer: The penalty can range from £1,200 to £2,400.

Example 2

Omar knowingly left £20,000 of tax out of his return and then sent HMRC false invoices to support the figures. Three years later he voluntarily told HMRC about the error before any enquiry started. Calculate the penalty range and interest cost for one year of delay on the underpaid tax, assuming interest of 8.50% for one year only.

Show the solution
  1. PLR = £20,000.
  2. Behaviour: the error was deliberate and false invoices were used to hide it, so it is deliberate and concealed.
  3. Disclosure: Omar told HMRC before any enquiry started and with no reason to think HMRC knew, so it is unprompted.
  4. Deliberate and concealed row: maximum 100%, minimum 30% for unprompted disclosure.
  5. Minimum penalty = 30% × £20,000 = £6,000.
  6. Maximum penalty = 100% × £20,000 = £20,000.
  7. Interest for one year = £20,000 × 8.50% = £1,700.
  8. Interest is charged in addition to the penalty.

Answer: The penalty can range from £6,000 to £20,000, plus interest of £1,700 for one year.

Exam tips

  • Copy the penalty table from the tax tables into your answer plan. It is given in the exam, so do not waste time memorising it exactly, but know the pattern.
  • Always justify the behaviour category using facts from the scenario. Marks are given for the reason, not only the label.
  • Give the range and then say where the penalty is likely to fall. This earns the professional judgement marks.
  • If a question asks for advice, link the penalty to disclosure. Explain that unprompted disclosure gives a lower minimum penalty.
  • Keep interest and penalty as separate lines in the answer.

Practice questions from Appropriateness of planning measures to a taxpayer's circumstances and objectives

Standard Penalties for Errors in Returns in other exams

The same ground in other exams, if you are preparing for more than one or want another angle on it.

Standard Penalties for Errors in Returns: frequently asked questions

What is potential lost revenue in a penalty for errors?

It is the extra tax that would have been lost if the error had not been corrected. You apply the penalty percentage to this amount. Work it out before anything else.

What is the difference between prompted and unprompted disclosure?

A disclosure is unprompted if the taxpayer makes it with no reason to believe HMRC has discovered or is about to discover the error. Otherwise it is prompted. Unprompted disclosure gives a lower minimum penalty.

Can a careless error lead to no penalty?

Yes. For a careless error with unprompted disclosure, the table shows a minimum penalty of 0%. The actual penalty depends on how HMRC rates the quality of the disclosure.

What are the maximum penalties for errors?

The maximums are 30% for careless, 70% for deliberate but not concealed, and 100% for deliberate and concealed errors. These are percentages of the potential lost revenue.