Self Assessment Software: Step-by-Step How-To for Personal Tax & Self Assessment Clients

To use self assessment software you register with HMRC for a Unique Taxpayer Reference (UTR) first, then use the software to enter your income and expenses, review the tax calculation it produces, and submit the return to HMRC online. The steps are the same whether you use HMRC's own service or a commercial package.

This guide is a walkthrough, not a product comparison. If you still need to pick which software to use and whether Making Tax Digital rules apply to you, read our guide to choosing self assessment software for Making Tax Digital first, then come back here for the actual setup, data entry and submission steps. For the wider list of deadlines this fits into, see key tax dates for Uber drivers.

Key takeaways

• Register for Self Assessment and get your UTR before you can submit anything, ideally months before the 31 January 2027 deadline.
• Set up your Government Gateway login and, if using commercial software, connect it to HMRC before you start entering figures.
• Enter income and expenses in the software's structured screens rather than one lump sum, so the calculation and any HMRC checks are accurate.
• Always review the tax calculation summary before you submit, comparing it to your own rough numbers.
• Keep the HMRC submission reference and a copy of the full return; you can amend online within 12 months if something was wrong.

What is self assessment software?

Self assessment software is any HMRC-compatible program or online service that lets you record your income and expenses, calculates the tax due, and submits your Self Assessment tax return (SA100) to HMRC electronically, replacing a paper form.

What do I need before I open the software?

Before opening any self assessment software you need your UTR, National Insurance number, Government Gateway credentials, and totals for every income source and allowable expense for the tax year. Without these the software cannot get past its first setup screen. If this is your first return as a driver, our guide for a first-time Uber driver's tax return covers what counts as income and expenses in more detail.

• Your 10-digit Unique Taxpayer Reference (UTR), sent by HMRC after registration.
• Government Gateway user ID and password, or the software's own way of linking to your HMRC account.
• National Insurance number.
• Total self-employment income for the tax year (Uber, Bolt, other private hire or delivery apps combined).
• Total allowable expenses, split by category (fuel, insurance, licensing, phone, mileage or vehicle costs).
• Details of any other income: employment, property, savings interest, pensions or dividends.
• Bank details if you're due a refund, or if you want to set up a Direct Debit for payment.

How do I register for Self Assessment before using software?

You register for Self Assessment on GOV.UK as newly self-employed, then wait for HMRC to post your UTR before any software can submit a return on your behalf. According to HMRC's registration guidance, you must register by 5 October 2026 if this is your first return covering the 2025/26 tax year, or you could get a penalty.

1. Go to GOV.UK and use the "Check if you need to send a Self Assessment tax return" tool if you're unsure.
2. Register as self-employed (or for other Self Assessment reasons) through the GOV.UK registration service.
3. Wait for your UTR to arrive by post; this normally takes around 10 working days but can take longer near the October deadline.
4. Activate your Government Gateway account and enrol for the Self Assessment online service using the activation code HMRC sends separately.
5. Once you have your UTR and an active Government Gateway login, you can open HMRC's online service or any commercial software and start your return.

How do I set up self assessment software for the first time?

First-time setup means creating an account with the software provider, answering a short questionnaire about your income sources, and connecting the software to your HMRC Government Gateway login so it can submit on your behalf. This normally takes 10 to 15 minutes.

1. Create an account with the software (email and password, or sign in with your Government Gateway details for HMRC's own service).
2. Confirm the tax year you're filing for; software defaults to the most recent tax year that's open for filing.
3. Answer the tailoring questions: self-employed, employed, landlord, pension income, capital gains, and so on. This decides which supplementary pages (SA103, SA105, SA109 etc) the software shows you.
4. Enter your UTR and National Insurance number where prompted.
5. Link the software to HMRC using your Government Gateway user ID and password, or follow the software's own authorisation flow.
6. Check the software confirms Self Assessment is enabled on that login; some accounts have several online services and only one may be tax-related.

How do I enter my income in self assessment software?

You enter income under the self-employment section, combining all Uber, Bolt, private hire and delivery platform earnings into one trading income total, plus any other income sources in their own separate sections. Software adds these together automatically for the tax calculation.

• Add up gross fares and platform earnings for the whole tax year, from every app you drove for, before any platform fees are deducted (most software has a separate box for platform commission as an expense).
• Use your annual tax summary from each platform as your starting figure, then check it against your own bank records.
• Enter any other self-employment income (private jobs, referral bonuses classed as trading income) in the same section.
• Enter employment income (a PAYE job alongside driving), property income, or savings interest in their own dedicated sections, not mixed into self-employment.
• Check the software's running total after each section; a total that looks too low or too high usually means a category was missed.

How do I enter expenses in self assessment software?

You enter expenses category by category, such as fuel, insurance, vehicle costs, phone and licensing, and the software subtracts the total from your income to work out your taxable profit. Most software separates simplified mileage from actual vehicle costs so you don't accidentally claim both.

How do I check the tax calculation before submitting?

Review the tax calculation summary screen line by line, checking your total income, total expenses, taxable profit, Class 2 and Class 4 National Insurance, and any Payments on Account, before you go anywhere near the submit button.

• Confirm every income source you have is listed; a missing section (like a small amount of bank interest) usually means you skipped a tailoring question.
• Check Class 4 National Insurance is showing if your profits are above the threshold; according to HMRC guidance on National Insurance rates, Class 4 NIC is charged at 6% and 2% for 2026/27.
• Look for Payments on Account for next year if your bill is over £1,000 and less than 80% of it was already collected through other means, as explained in HMRC's guidance on payments on account.
• Compare the total bill to your own rough estimate; a large unexpected difference is worth investigating before you submit, not after. Our tax calculator is a quick way to sense-check the software's figure before you submit.

How do I submit my return through the software?

You submit by confirming the declaration that your return is complete and accurate, then clicking submit; the software sends the data to HMRC and you should receive an acknowledgement with a submission reference number within minutes.

1. Review every section one final time using the software's summary or review screen.
2. Re-enter your Government Gateway password if prompted, to confirm the submission is authorised by you.
3. Tick the declaration confirming the information is correct and complete.
4. Click submit; most software shows a progress indicator while it sends the return to HMRC.
5. Save or print the confirmation screen and note the submission reference number.
6. Check your HMRC online account within a day or two to confirm the return shows as received and note the tax calculation reference.

What if the software won't let me submit?

A blocked submission is almost always a missing mandatory field, an inactive Self Assessment enrolment on your Government Gateway login, or a mismatch between your UTR and National Insurance number, not a fault with the software itself.

• Check every section marked as incomplete or flagged with a warning icon.
• Confirm Self Assessment shows as an active service on the Government Gateway account you're using; some people accidentally log in with a PAYE-only account.
• Double-check your UTR and National Insurance number are typed correctly, with no transposed digits.
• If the software still fails, HMRC's own online service can usually be used as a fallback for the same tax year.

Common mistakes when using self assessment software

Illustrative example: entering a year's driving income into software

Illustrative example. Priya drives for Uber and does occasional Deliveroo shifts. Over the 2025/26 tax year her platform summaries show £34,200 combined gross income. She claims simplified mileage for 11,400 business miles and £980 of phone, insurance excess and licensing costs.

In the software she enters £34,200 as self-employment income, then calculates her mileage allowance: 10,000 miles at 55p (£5,500) plus 1,400 miles at 25p (£350), totalling £5,850. Adding her £980 of other expenses gives total allowable expenses of £6,830, leaving taxable profit of £27,370 before her personal allowance and any other income are applied by the calculation screen.

Key terms

• UTR (Unique Taxpayer Reference): the 10-digit number HMRC issues when you register, needed to file any return.
• MTD (Making Tax Digital): HMRC's programme requiring digital records and quarterly updates once qualifying income passes set thresholds.
• NIC (National Insurance Contributions): Class 4 NIC is paid by self-employed people on profits above a threshold, calculated automatically by most software.
• PHV (Private Hire Vehicle): the licensing category that covers Uber, Bolt and most minicab driving.
• POA (Payments on Account): advance payments toward next year's tax bill, due 31 January and 31 July.

How Uber Driver Accountant helps

If you'd rather not enter every figure yourself, Uber Driver Accountant's personal tax service handles registration, data entry, the calculation check and submission for you, for a fixed fee from £20 a month. We work only with drivers and are entirely independent of Uber, Bolt and any other platform.

We also help if you've already started a return in software and got stuck, checking your figures before you submit rather than after HMRC has queried them. See our pricing for the fixed monthly fees.

Last reviewed

Last reviewed 28 September 2026 by the Uber Driver Accountant tax team.

Ready to get your return filed correctly and on time? Contact Uber Driver Accountant and we'll take the software and the submission off your hands.

This article is general information, not personal tax advice. Every driver's circumstances differ, so speak to a qualified accountant before relying on it, and seek professional representation if HMRC raises a dispute or penalty on your account.