HMRC October ‘double deadline’ as accountant warns over ‘instant £100 fine’ | Personal Finance | Finance
Brits could be instantly £100 poorer if they miss HMRC’s double tax deadline this October, with penalties potentially escalating to £1,600 for those who procrastinate. The warning comes from Andrea L Richards, an accountant and CEO of Accounts Navigator.
She has issued a reminder about the October 5 self-assessment registration cut-off date and the October 31 paper return deadline, emphasising how missing these dates can result in hefty fines and charges for households.
HMRC October 2025 deadlines
Who needs to file to HMRC in October?
Andrea explained: “A tax return is required if you were self-employed and earned more than £1,000, were in a business partnership, needed to pay Capital Gains Tax, or were liable for the High Income Child Benefit Charge outside of PAYE. You may also need to file if you received untaxed income, such as rental earnings, tips, savings interest, or foreign income.”
October 5, 2025, HMRC deadline
Andrea said: “Anyone needing to submit a tax return for the first time must notify HMRC by October 5, 2025. If you register late, your filing deadline is extended to three months from when HMRC issues a return or notice. Delaying registration can increase the risk of penalties if the return isn’t submitted on time.”
October 31, 2025, HMRC deadline paper return deadline
Andrea warned: “Paper tax returns for the 2024/25 year must reach HMRC by October 31, 2025. Missing this initial deadline triggers an automatic £100 penalty, even if no tax is owed, and further charges can accumulate quickly.”
Online filing after missing October deadline
On the topic of online filing after missing the October deadline, Andrea cautioned: “People might think that if they miss the paper deadline, filing online by January 31, 2026, will automatically avoid penalties, but HMRC calculates late filing penalties from the date the first return is received. Filing online after missing October may avoid penalties in certain situations, but it’s safer to meet the original October deadline whenever possible.”
How HMRC late filing penalties escalate
Andrea said: “If a return is more than three months late, daily penalties of £10 apply, up to £900. Six months late brings a further charge of £300 or 5% of tax due and after 12 months another £300 or 5% is added.
“In total, penalties for serious delays can reach £1,600, in addition to any tax owed. Filing early avoids these escalating costs.”
Consequences of not filing
Andrea said: “If a return isn’t filed at all, HMRC can formally estimate the tax you owe and demand immediate payment with interest, and in extreme cases, court proceedings.”
Appeals against filing late
Andrea stated: “HMRC may consider appeals against late filing penalties, but only after the return has been filed. Penalties can be cancelled only if you have a ‘reasonable excuse,’ which must exist throughout the period of late filing.”
