Seven Overlooked Deductions to Track Before the 31 January 2027 Deadline

January deadlines have a habit of arriving early. With 31 January 2027 now roughly twelve weeks away, the sensible response is not panic — it is to open a folder, gather what already exists, and check it against a list. A large proportion of people filing a return are entitled to some relief they have never claimed. The seven below are the ones that go missing most often.

Which year is actually being filed?

Two tax years meet at this deadline, which is a common source of muddle. The return filed by 31 January 2027 reports income for 2025/26, the year that ran from 6 April 2025 to 5 April 2026. On the same date, the first payment on account towards 2026/27 usually falls due.

Meanwhile the current year, 2026/27, is still running until 5 April 2027. Anything you record between now and then feeds the return due on 31 January 2028. The deductions below apply to both years, so the work you do this month pays twice over.

One general rule frames everything: for the self-employed, costs must be incurred wholly and exclusively for the trade. For employees, the bar is higher — wholly, exclusively and necessarily in the performance of the duties. Beyond that, the principle is simply that you can only claim what you can support.

1. Professional subscriptions and memberships

Fees paid to a professional body on HMRC's approved list are deductible, provided membership is relevant to the work you do. Annual subscriptions to trade associations, regulatory bodies and learned societies usually qualify; one-off life memberships and subscriptions that confer a personal benefit generally do not. Employees whose employer will not reimburse the fee can claim relief through self-assessment.

2. Mileage

If you use your own vehicle for business journeys, the simplified rates are 45p per mile for the first 10,000 miles and 25p thereafter, with 24p for motorcycles and 20p for bicycles. Employees can claim relief on business mileage that was not reimbursed at those rates.

The trap is mixing methods. You either claim mileage rates or you claim a proportion of actual running costs, not both in the same year for the same vehicle. A contemporaneous mileage log — date, destination, purpose, miles — is the evidence that makes the claim stand up.

3. Working from home

Employees who work from home under an arrangement with their employer can claim a flat £6 per week without producing a single bill. The alternative is a reasonable apportionment of heating, lighting and broadband, supported by evidence.

For the self-employed, simplified expenses offer a flat monthly amount based on hours worked at home: £10 for 25 to 50 hours, £18 for 51 to 100 hours, and £26 for 101 hours or more. Actual costs apportioned on a sensible basis can be claimed instead if they are higher.

4. Equipment, software and capital allowances

The annual investment allowance currently stands at £1 million, which in practice means most sole traders and partners can deduct the full cost of equipment in the year of purchase. Laptops, printers, desks, tools and specialist kit all count. Software subscriptions and cloud storage are usually treated as ordinary running costs.

Employees can claim for tools and equipment they are required to buy and that their employer does not provide. Remember that anything with a private use element needs to be apportioned.

5. Pension contributions

Private pension contributions attract relief at source: the provider adds 20% to whatever you pay. Higher and additional rate taxpayers then claim the extra through self-assessment by entering the gross contribution — the amount paid multiplied by 1.25. The effect is to extend the basic rate band, which can be valuable at the margin.

The annual allowance is £60,000 for most people, tapering for very high earners and reduced for those who have already drawn flexibly from a pension. Contributions made by 5 April 2027 belong to 2026/27.

6. Gift Aid

Donations to UK charities under Gift Aid are treated as paid net of basic rate tax, so HMRC effectively tops them up. For the donor, the grossed-up value extends the basic rate band in the same way a pension contribution does, which reduces the amount exposed to higher rates.

The only evidence you need is a record of what you gave — bank statements, a standing order schedule, or a sponsorship page will do. Gift Aid declared on a return is one of the simplest ways to trim a bill, and one of the most frequently omitted.

7. The odds and ends

A cluster of smaller costs slips through every year:

• Accountancy and bookkeeping fees for preparing your accounts or return.
• Business bank charges and card fees, including the cut platforms and payment processors take.
• Insurance — professional indemnity, public liability, cover for tools or stock.
• Trade journals and reference materials relevant to your work.
• Training that updates existing skills, as distinct from training that equips you for an entirely new trade.
• Bad debts that are genuinely irrecoverable, written off in the year.
• A business proportion of phone and broadband, based on a defensible percentage.

And if your trading income is under £1,000, the trading allowance may let you skip the arithmetic altogether — although it replaces expenses rather than adding to them, so compare before you choose.

What to gather this month

A single afternoon is usually enough. Collect bank and card statements covering the whole of 2025/26, receipts and invoices, a mileage record, P60s and P45s, dividend and interest vouchers, pension contribution statements, Gift Aid records, and anything relating to student loan repayments. Photograph paper receipts as you go — thermal paper fades, and HMRC can ask to see records for five years after the filing deadline.

If you have not yet registered for self-assessment for 2025/26, do it now. The formal notification deadline of 5 October 2026 has passed, but HMRC still expects the return, and registering late is far better than not registering at all.

Why November beats January

Filing early carries no penalty and removes the risk of a systems crash on deadline day — which, this time, falls on a Sunday. Late filing triggers an automatic £100 penalty, followed by daily charges after three months and further fixed or percentage penalties at six and twelve months. Late payment attracts its own 5% surcharges and interest.

If the bill is genuinely unaffordable, ring HMRC before the deadline rather than after it and ask about a Time to Pay arrangement. These are commonplace and routinely agreed.

Starting now gives you twelve weeks to find the receipts, check the numbers and, in all likelihood, discover a deduction or two you would otherwise have missed.