December 30: HMRC warns £100 fines as Self Assessment deadline nears
The self assessment tax return deadline is close, and HMRC has warned of automatic £100 fines if you miss 31 January. HMRC reported 4,606 Christmas Day filings, showing many are getting ahead. If you wanted PAYE coding to spread what you owe, that option ended on 30 December. Interest builds on late payments, so filing early helps cut costs and stress. We explain who must file, cash flow moves to consider, and how to prepare for Making Tax Digital from April 2026.
HMRC fines and key dates
Miss the 31 January deadline and HMRC issues an automatic £100 penalty, even if no tax is due. Interest also applies to late payments until cleared. HMRC has urged early action after 4,606 returns were filed on Christmas Day, highlighting momentum among taxpayers. See the official update from HMRC’s press office for festive filing figures and reminders here.
Many prefer HMRC to collect underpaid tax through their PAYE code. That route closed on 30 December for 2023/24 returns. If you missed it, plan to pay by 31 January to avoid extra costs. Media reports underline that HMRC will apply automatic fines where rules are breached. Read more context here.
Who must file and what to include
You must file a self assessment tax return if you are self-employed, a landlord, a partner in a partnership, or had untaxed income. Investors may need to report dividends, interest, and capital gains. Check if your total income, benefits, or crypto gains trigger a filing need. If unsure, use HMRC’s online checker and keep evidence to support entries.
Collect P60s, P45s, P11Ds, bank interest, dividend vouchers, invoices, rent schedules, expense records, and pension or Gift Aid statements. Include student loan details if repayments apply. Many will also face payments on account. Filing a complete self assessment tax return early reduces correction risks and gives more time to budget before 31 January.
Cash flow and payments on account
Estimate your bill now. Log in to your HMRC account to view tax due, payments on account, and deadlines. Many will have two instalments in January and July. Build a short cash flow plan, reserve funds for VAT or NICs if relevant, and avoid using credit that adds high interest. Early filing helps you act faster.
If you cannot pay the full amount, file the self assessment tax return first, then apply for a Time to Pay plan online. Agreements depend on your debt and affordability. Paying something now reduces interest costs. Keep all returns and payments up to date, or HMRC may withdraw the plan and add more charges.
Making Tax Digital starts April 2026
From April 2026, HMRC’s Making Tax Digital for Income Tax begins for self-employed people and landlords. You will keep digital records and send quarterly updates, then an end-of-period statement. Choose software that supports digital links. Getting used to regular bookkeeping now can make the switch smoother and cut errors next year.
Map your income and costs, pick compliant software, and tidy your chart of accounts. Keep receipts digitally and reconcile bank transactions monthly. Run test summaries to spot gaps. Filing a timely self assessment tax return this year creates a clean baseline, so your 2026 quarterly updates and year-end statement are more accurate.
Final Thoughts
HMRC’s message is clear: file your self assessment tax return early, pay what you owe by 31 January, and avoid the £100 penalty plus interest. If you needed PAYE coding, that closed on 30 December, so plan for a one-off payment or a Time to Pay plan after filing. Gather records now, check payments on account, and confirm amounts in your HMRC account. Sole traders and landlords should also use 2025 to prepare for Making Tax Digital starting April 2026 by moving to digital records and regular reconciliations. Early action lowers errors, supports cash flow, and helps you stay compliant at the lowest cost.
FAQs
HMRC will issue an automatic £100 penalty for a late self assessment tax return, even if you do not owe tax. Interest applies to late payment until you clear the balance. Penalties can increase the longer you delay, so file as soon as possible and pay what you can.
Yes, but only if you filed by 30 December and met HMRC criteria. After that date, PAYE coding for the current return is not available. If you missed it, pay by 31 January or consider a Time to Pay plan. Filing first is required before setting up an instalment plan.
You usually need to file if you are self-employed, a landlord, a partner in a partnership, or received untaxed income. Some investors must report dividends, interest, or capital gains. You may also need to file if your income or benefits changed. Use HMRC’s checker if unsure.
Move to digital bookkeeping in 2025. Choose compatible software, keep digital records for income and expenses, and reconcile bank feeds monthly. Run test quarterly summaries to find gaps. A clean, timely self assessment tax return this year gives you accurate opening data for 2026 updates.
Disclaimer:
The content shared by Meyka AI PTY LTD is solely for research and informational purposes. Meyka is not a financial advisory service, and the information provided should not be considered investment or trading advice.
