Self Assessment: 100 days left, Winter Fuel now pre-filled

What the 100 days covers

HMRC published a press release on 23 October 2026 stating that there are 100 days to the Self Assessment deadline for the 2025 to 2026 tax year. The online filing and payment deadline is 31 January 2027, and around 12 million people are expected to submit a return by that date. The 100 day countdown therefore runs from the publication date to the end of January 2027, and covers both the submission of the return and the payment of any tax owed for the year.

The 2025 to 2026 tax year is the period covered by the return. Customers with PAYE income who file online before 30 December 2026 can have tax owed up to the limit collected through their tax code, which moves collection into the following year's PAYE rather than requiring a separate payment by 31 January 2027. New filers must register first to get a Unique Taxpayer Reference (UTR), and GOV.UK has a checker for whether a return is needed. People signed up to Making Tax Digital for Income Tax still file the 2025 to 2026 return the usual way and pay by 31 January 2027. The paper return deadline for 2025 to 2026 is 31 October 2026.

Winter Fuel Payment on your return

The 2025 Winter Fuel Payment, and the Pension Age Winter Heating Payment in Scotland, is pre-populated in online returns where possible. Where the figure is not pre-populated, it must be added manually, and paper filers add it manually in all cases. The payment is not simply ignored for higher income households: if total income is over £35,000, the Winter Fuel Payment is paid back through the Self Assessment bill. That means the amount appears as a charge within the return rather than as a separate recovery process.

The practical effect is that the return now carries a direct link between the Winter Fuel Payment received and the level of total income for the year. A customer whose income exceeds £35,000 will see the payment recovered through the Self Assessment calculation, so the amount is settled with the rest of the tax bill rather than through a standalone demand. Because the figure is pre-populated online where possible, the main risk for online filers is an incorrect or missing entry that needs checking before submission. Paper filers carry the full task of entering the amount themselves, which places the accuracy of the entry entirely with the customer.

Child Benefit charge details pre-filled

Around 300,000 customers paying the High Income Child Benefit Charge will see Child Benefit payment details pre-populated on their returns. The pre-population reduces the need to source the payment figures separately, but the charge itself still depends on the income position for the year. Some of these customers can pay the charge through PAYE instead of through the return, which moves collection into the tax code rather than into the Self Assessment balancing payment.

The 30 December 2026 date is relevant here as well as for other PAYE income: customers who file online before that date can have tax owed up to the limit collected through their tax code. For Child Benefit charge payers who are eligible to pay through PAYE, that route sits alongside the pre-populated details on the return. People signed up to Making Tax Digital for Income Tax are not exempt from the normal process: they still file the 2025 to 2026 return the usual way and pay by 31 January 2027. The pre-population of Child Benefit details therefore applies within the standard return, not through a separate digital route.

Crypto gains and other items to declare

Cryptoasset gains above the £3,000 Capital Gains Tax annual exempt amount must be declared on the 2025 to 2026 return. The £3,000 figure is the annual exempt amount for Capital Gains Tax, so gains above that level fall to be reported through Self Assessment rather than being covered by the exemption. The requirement applies to the 2025 to 2026 return specifically, and the gain is declared within the Capital Gains Tax section of the return alongside other chargeable gains.

The cryptoasset item sits alongside the other changes for this year's return: the pre-populated Winter Fuel Payment and the pre-populated Child Benefit details for around 300,000 High Income Child Benefit Charge payers. Each of these items depends on the customer's own figures for the year, and each is entered or checked within the online return where pre-population applies. Where pre-population does not apply, the figures must be added manually, and paper filers add them manually in all cases. The return for 2025 to 2026 therefore brings together income, benefits and gains in a single filing due by 31 January 2027.

Penalties and payment plans if you miss it

The late filing penalty is £100 immediately. After 3 months, a penalty of £10 a day applies for up to 90 days, up to £900. After 6 months, a further 5 percent of tax due or £300 applies, whichever is higher, and the same again after 12 months. Late payment interest is charged from 1 February 2027. The penalty ladder therefore escalates from a fixed £100 at the deadline through daily charges and percentage charges, with the percentage element tied to the tax due or a £300 floor.

HMRC online payment plans, known as Time to Pay, are available for Self Assessment debts up to £30,000 once the return is filed. The plan route depends on the return being filed first, so the filing deadline and the payment arrangement are separate steps. HMRC also warns of phishing: it never asks for sign-in details by text or email link. Customers with PAYE income who file online before 30 December 2026 can have tax owed up to the limit collected through their tax code, which is a collection route rather than a payment plan.

Source: HMRC press release, 23 October 2026.

Related coverage on Kael Tripton: Self Assessment: Child Benefit pre-filled on 300,000 returns, Self Assessment: register by 5 October or face a penalty, Self Assessment Tax Return UK 2025/26: Deadlines, Who Must File and How to Submit, Late Inheritance Tax Return UK: Penalties, Interest and How to Appeal, High Income Child Benefit Charge UK.

Frequently asked questions

When is the Self Assessment deadline for the 2025 to 2026 tax year?

The online filing and payment deadline is 31 January 2027. HMRC said on 23 October 2026 that there were 100 days to the deadline. Around 12 million people are expected to submit a return by 31 January 2027.

Is the 2025 Winter Fuel Payment pre-filled on the return?

The 2025 Winter Fuel Payment, and the Pension Age Winter Heating Payment in Scotland, is pre-populated in online returns where possible. Paper filers add it manually. If total income is over £35,000, the payment is paid back through the Self Assessment bill.

Do Child Benefit details appear automatically for High Income Child Benefit Charge payers?

Around 300,000 customers paying the High Income Child Benefit Charge will see Child Benefit payment details pre-populated. Some can pay the charge through PAYE instead. Customers who file online before 30 December 2026 can have tax owed up to the limit collected through their tax code.

Do crypto gains have to be declared?

Cryptoasset gains above the £3,000 Capital Gains Tax annual exempt amount must be declared on the 2025 to 2026 return.

What are the late filing penalties?

The late filing penalty is £100 immediately. After 3 months, £10 a day applies for up to 90 days, up to £900. After 6 months, a further 5 percent of tax due or £300 applies, whichever is higher, and the same again after 12 months. Late payment interest is charged from 1 February 2027.