UK Corporation Tax Late Filing Penalties: HMRC Notice Pause Extended to End-July 2026
HMRC Agent Update 145 confirms the temporary pause on automatic Corporation Tax late-filing penalty notices — needed while systems reflect higher penalties from 1 April 2026 — now runs to the end of July 2026. Late returns still attract the increased penalties.
In Agent Update issue 145, HM Revenue & Customs reminded agents that automatic Corporation Tax late-filing penalty notices remain paused while HMRC finishes updating systems for the higher penalty amounts that apply to returns due on or after 1 April 2026. The system work was originally expected by 30 June 2026 and is now expected to complete by the end of July 2026.
The pause prevents customers receiving letters that show incorrect (pre-increase) amounts. It is not a penalty holiday. Companies that file after the deadline remain liable for the increased penalties, and further penalties can apply if the return stays outstanding.
What changed from 1 April 2026
Late filing penalties for Corporation Tax increased for returns due on or after 1 April 2026. Professional bodies summarising the Budget 2025 measure report the fixed penalties doubling under Schedule 18 Finance Act 1998 — for example, a late return moving from £100 to £200, and a return more than three months late from £200 to £400, with higher amounts where there are three successive failures.
HMRC paused automatic notices so the new figures print correctly when notices resume. Agents should assume notices will issue automatically from late July once the update completes, unless a later Agent Update says otherwise.
What companies and agents should tell clients
Continue filing Corporation Tax returns on time — a delayed notice does not mean no penalty applies. If a client filed late and has not received a notice, they do not need to contact HMRC to chase it; notices are expected to issue automatically when the system update finishes.
Diary CT600 and accounts filing dates now. After the closure of HMRC’s free online company accounts and tax return service at the end of March 2026, most companies need commercial filing software or an agent — do not leave the first late return of the new penalty regime to last-minute portal confusion.
Separate payment and filing: paying Corporation Tax on time does not cure a late return, and a late return can still trigger filing penalties even where tax is paid.
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Related reading
For the mid-August operational reminder under the doubled tariff now shown on GOV.UK, read the live penalties briefing.
If your filing workflow still assumes HMRC’s free CT600 portal, update process notes after the April 2026 closure.
Use the free tax calculator for illustrative liability estimates only — not a Corporation Tax or penalty computation.
Sources & references
This article draws on official guidance from the sources below.
- Issue 145 of Agent Update — Corporation Tax late filing penalties temporary delay
HM Revenue & Customs · Accessed 2026-07-30 - Issue 142 of Agent Update — Corporation Tax late filing penalties temporary delay to notices
HM Revenue & Customs · Accessed 2026-07-30 - Automatic Corporation Tax penalty notices temporarily paused as HMRC updates systems
Association of Taxation Technicians · Accessed 2026-07-30
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