Guides › HMRC Penalties for Errors on Your Return: Careless to 30%
HMRC Penalties for Errors on Your Return: Careless to 30%
General information, not tax advice. We are not HMRC and are not affiliated with it. Check GOV.UK. Last checked against GOV.UK: 17 October 2026. Anything marked expected should be re-checked. Examples use made-up figures. This page contains no affiliate links. Do not enter personal identifiers (National Insurance number, UTR, name, date of birth) on this site.
Short answer: GOV.UK says that if you took reasonable care and your return was still inaccurate, HMRC will not charge a penalty. If you did not take reasonable care, the penalty is a percentage of the extra tax due from correcting the error ("potential lost revenue"). HMRC's Compliance Handbook gives the standard (onshore) ranges: careless 0%-30% if you tell HMRC before they find it (unprompted) or 15%-30% if prompted; deliberate 20%-70% or 35%-70%; deliberate and concealed 30%-100% or 50%-100%. HMRC can reduce the penalty for telling it about the error, helping it work out the extra tax and giving it access to check figures; for an unprompted careless error the penalty can be reduced to nil (CH82470).
Table (CH82470, standard onshore rates)
| Behaviour | Unprompted: min–max | Prompted: min–max |
|---|---|---|
| Careless | 0%–30% | 15%–30% |
| Deliberate | 20%–70% | 35%–70% |
| Deliberate and concealed | 30%–100% | 50%–100% |
| HMRC says it is possible to reduce a careless, unprompted penalty to nil. Higher penalties can apply where the error involves an offshore matter and the tax is income tax or capital gains tax. |
Reasonable care (GOV.UK)
- Keep records that let you send accurate returns, and ask HMRC or an adviser if you are unsure.
- If you use a tax adviser, you must still give accurate and complete information.
- If you get a penalty notice, you must pay or appeal within 30 days of the date on it.
Other standard maximums in CH82120: an inaccuracy due to the deliberate behaviour of another person is 100% of potential lost revenue, and an understated assessment you did not notify is 30%.
Found an error later?
The Compliance Handbook (CH82120) says that if you discover an inaccuracy and do not take reasonable steps to tell HMRC, it is treated as careless even if it was not careless when made. Our page on changing a return explains how to correct one: Change a return after filing.
Made-up illustration
A careless mistake leads to £3,000 of extra tax (the potential lost revenue). If you tell HMRC before they find it (an unprompted disclosure), the penalty can be anywhere from £0 to £900 (0% to 30%); if HMRC finds it first (a prompted disclosure), it is between £450 and £900 (15% to 30%). Where it falls in the range depends on how much you tell, help and give access (CH82430). This is not a prediction of your penalty.
Related
Change a return after filing · Missed the deadline? · Late-payment interest
FAQ
Is a late filing penalty the same thing? No; those are separate (see the missed-deadline page).
Does interest also apply? Interest on extra tax is separate from the penalty; see the interest page.
What we could not verify
- Penalty rates for offshore matters (CH116000+ not read).
- How HMRC sets the point within each range (CH82430-82460 titles seen; not read in full).
- Dates from which each tax's rules apply (CH81011 not read).
- The compliance factsheet CC/FS7A: the figures on this page come from the Compliance Handbook, not the factsheet.
Sources (official)
- GOV.UK (HMRC), CH82470: Penalties for Inaccuracies: maximum and minimum penalties — https://www.gov.uk/hmrc-internal-manuals/compliance-handbook/ch82470 (read in full 17 October 2026; no review date shown)
- GOV.UK (HMRC), Reasonable care: tax returns and other documents (published 14 February 2018) — https://www.gov.uk/guidance/reasonable-care-tax-returns-and-other-documents (read in full 17 October 2026)
- GOV.UK (HMRC), CH82120: Amount of penalty — introduction — https://www.gov.uk/hmrc-internal-manuals/compliance-handbook/ch82120 (read 17 October 2026)
- GOV.UK (HMRC), Compliance checks: penalties for inaccuracies, factsheet CC/FS7A — https://www.gov.uk/government/publications/compliance-checks-penalties-for-inaccuracies-in-returns-or-documents-ccfs7a (search excerpt, 17 October 2026)
Deadlines calendar → Penalty estimator →
Not tax advice. See the disclosure.