What you need to know
The easiest way to file a UK tax return is using HMRC-recognised software such as Pie.tax, which guides you from tracking income and expenses throughout the year to calculating your tax and submitting directly to HMRC.
Filing through dedicated software is faster, clearer, and less error-prone than using HMRC's portal alone.
At a Glance
For the 2025–2026 tax year, HMRC deadlines are: 31 January for online submissions and 31 October for paper returns. Tax software is ideal for self-employed individuals, freelancers, sole traders, landlords, and anyone who wants a guided, accurate, stress-free filing experience.
What Is a UK Tax Return?
A tax return is a formal declaration of income, gains, and allowable expenses for a UK tax year (6 April – 5 April). HMRC uses this to calculate your Income Tax and National Insurance.
Most employees pay tax automatically via PAYE and rarely need to file.However, self-employed individuals, landlords, company directors, and anyone with income outside PAYE must register for Self Assessment.
The core form is SA100, with supplementary forms like SA103 (self-employment), SA105 (property), and SA108 (capital gains). Software like Pie.tax automatically selects and fills relevant sections, reducing errors and guesswork.
Who Must File a Self Assessment?
You must file if you were self-employed with gross income over £1,000, a partner in a business partnership, a company director, earned over £100,000, had untaxed income over £2,500, or capital gains above the annual exemption.
Other triggers include receiving Child Benefit above certain thresholds, foreign income, or claiming reliefs not covered by PAYE. Formal HMRC notices also require filing.
Best Way to File (2025–2026)
You can file via HMRC’s portal, a paper SA100, or HMRC-recognised software. For most self-employed people, landlords, and freelancers, software is faster and more reliable.
Pie.tax connects directly to HMRC, guides you in plain English, calculates your liability in real time, and lets you start, pause, and return to your filing anytime.
Unlike HMRC’s portal, Pie.tax combines year-round tracking, real-time tax estimates, and direct HMRC submission, making filing a confirmation rather than a deadline scramble.
Why Use Tax Software
HMRC’s portal is compliance-focused and technical, offering no guidance on claims or tax estimates. Software like Pie.tax simplifies filing with plain language, prompts for reliefs and allowances, and supports year-round record keeping. With Making Tax Digital for Income Tax coming in April 2026, software ensures smooth compliance with quarterly updates, leveraging AI tools for self-employed tax returns.
Who Pie.tax Is For
Pie.tax suits anyone filing Self Assessment, particularly:
- Sole traders and freelancers seeking clear guidance
- Landlords with one or more properties
- Individuals with multiple income streams
- Anyone preparing for MTD for ITSA compliance
How to File Using Pie.tax
Filing through Pie.tax is simple:
- Register for Self Assessment – Sign up at gov.uk/register-for-self-assessment by 5 October after your first tax year. HMRC sends your 10-digit UTR, and you need a Government Gateway ID to connect Pie.tax.
- Set Up Pie.tax – Download the app and connect to HMRC securely using their official API.
- Track Income and Expenses – Log earnings and expenses as they happen. Pie.tax gives real-time tax estimates and avoids the January filing rush.
- Review and Claim Reliefs – Pie.tax checks for key reliefs like Personal Allowance, Marriage Allowance, Trading Allowance, Property Allowance, Gift Aid, and pension contributions.These are often missed but save money.
- Submit to HMRC – File directly through the app and receive a confirmation reference as proof. HMRC processes submissions like any other online return.
Documents You Need
Prepare your:
- National Insurance number, UTR, and Government Gateway ID
- P60/P45, P11D, invoices, bank interest, dividends, rental income, pension info
- Business receipts, mileage logs, and expense records
- Gift Aid and pension contribution statements
- Property or investment sale records if applicable
Pie.tax already captures many of these records year-round, reducing the pre-filing checklist, including digital content income.
Claiming Reliefs and Allowances
Pie.tax prompts for all common allowances: Personal Allowance (£12,570), Marriage Allowance, Trading and Property Allowances, Gift Aid, and additional pension contributions. Filing through HMRC’s portal alone risks missing these savings.
Filing Late Returns
If you miss deadlines, file immediately. Penalties start at £100 (1 February) and escalate with time. Interest accrues from 31 January. If unable to pay, contact HMRC for a Time to Pay arrangement. Valid excuses for appeals include serious illness or HMRC portal failures.
Making Tax Digital for ITSA
From April 2026, qualifying taxpayers must submit quarterly digital updates via HMRC-compatible software. Thresholds reduce over time, making year-round record keeping essential. Pie.tax prepares you in advance, ensuring smooth transition to MTD compliance.
Common Mistakes
- Not declaring all income
- Confusing turnover with profit
- Claiming non-allowable costs
- Missing registration deadlines
- Pie.tax reduces these risks with real-time estimates, guided prompts, and record keeping.
HMRC Checks and Amendments
HMRC cross-references data from banks, DVLA, Land Registry, and other sources. Formal enquiries follow Section 9A notices, with rights for representation and appeals. Returns can be amended within 12 months of the January deadline.
Final Summary
Filing a Self Assessment tax return is mandatory for many UK taxpayers. HMRC-recognised software is the most efficient route. Pie.tax simplifies the process, from year-round tracking to HMRC submission, reduces errors, and prepares you for MTD compliance. File early to avoid penalties and use software for stress-free, accurate returns.
