This is a beginner’s guide to self-assessment, designed to help sole traders who are just starting out or performing a tax return for the first time. We’ll cover basics such as registering for self-assessment, what documentation you’ll need and what software can help.
We’ll also include additional information like the upcoming year’s deadlines and whether you need to hire an accountant.
Read on for the full guide or go straight to your preferred section.
What is self-assessment?
Do I need to do self-assessment?
How do I register for self-assessment?
Which documents do I need to submit self-assessment?
How to submit your tax return
Do I need to hire an accountant?
What software can help with self-assessment?
Important self-assessment dates
I’m still unsure about submitting my tax return – is there any support available?
What is self-assessment?
Self-assessment is the method used to calculate how much tax you need to pay on your annual earnings.
Do I need to do self-assessment?
You’ll need to do self-assessment if:
You’re registered as sole trader and have earned more than £1,000 (pre-tax)
You have to pay the High Income Child Benefit Charge
If you’re not sure, check the government tool which will tell you if you need to file for self-assessment.
How do I register for self-assessment?
The government website has a separate online tool that you can use to register for self-assessment.
If you’ve already registered, you don’t need to do it again. However, if you registered for self-assessment last year but didn’t do a tax return, you’re going to have to do it again this year.
Which documents do I need to submit self-assessment?
This will depend on whether you’re employed or self-employed, and if you have any other forms of income such as benefits or a rental property.
Where it applies to you, you’ll need:
Unique taxpayer reference (UTR)
Government Gateway user ID
National Insurance number
Invoices you’ve issued
Salary and income from other jobs
Benefits from your employer
Income from pensions or state benefit
Income from rental properties
Student loan plan and any sums that you’ve repaid
How to submit your tax return
Once you’ve registered, you can submit your self-assessment online at gov.uk.
Accuracy is key with tax returns, so one thing you must do is keep accurate records of the following throughout the year:
Any information around sales and income
A record of every business expense you intend to claim
All VAT records (if you’re registered for VAT, that is)
PAYE records (if you have employees)
All personal income records
Keep all of these for at least five years after your last self-assessment submission.
Do I need to hire an accountant?
Though there’s no requirement for an accountant, but you’d be leaving yourself wide open to costly errors such as miscalculations and incomplete information. Over-claiming and under-claiming on allowable expenses are also common issues, as is not including all income.
What’s more, an accountant can make sure you claim all of the expenses that you’re entitled to – and the ones you might not know about.
It’s also worth checking who you have your business bank account with as some may have access to an accountancy firm as part of their package. Even if they don’t, business bank accounts often integrate with accountancy platforms, making managing your finances substantially easier.
What software can help with self-assessment?
Software can be an enormous help when you’re filing your self-assessment.
The software you choose must meet the following requirements:
Work with tax calculations that adhere to UK standards and compatible with our tax year (April 6 – April 5)
Has to integrate with UK bank accounts
Can handle income from different sources – employed, self-employed, property, pension, etc.
Has to meet UK data security requirements
Sending out deadline reminders
From April 2026, software must be compatible with Making Tax Digital if you have an annual income of over £50,000. You must use it to keep digital records, submit summary income and expense data every quarter and finalise your business income at year end.
Sage’s self-assessment software records transactions and allows you to take pictures and scan your expenses when you’re out and about. AI-powered automation sorts your expenses into categories too. From there, you can generate a filled-out self-assessment form, put it on the government portal and submit.
Sage Business Cloud Accounting
Sage is a cloud-based accounting tool for small businesses, recognised by HMRC and compatible with Making Tax Digital. It offers features like invoicing, VAT submissions, bank syncing, and AI-powered tools. Plans scale with your business needs, from sole traders to growing teams.
Plans and pricing (excl. VAT):
Start – £1.80/month (then £18): Invoicing, bank reconciliation, VAT submissions
Standard – £3.90/month (then £39): Includes Start + CIS, cashflow, quotes, advanced reporting
Plus – £5.90/month (then £59): Includes Standard + inventory, multi-currency, and budgeting
Intro offer: 90 per cent off for six months
Check out Sage’s self-assessment software to discover more
QuickBooks
QuickBooks is a popular cloud-based accounting platform, ideal for sole traders to growing SMEs. HMRC-recognised for Making Tax Digital, it offers invoicing, VAT and CIS submissions, real-time insights, and AI-powered bookkeeping.
Plans and pricing (excl. VAT):
Sole Trader – £1/month (then £10): Invoicing, cashflow, MTD for Income Tax, Self Assessment tools
Simple Start – £1.60/month (then £16): Adds VAT submissions, CIS returns, and accountant access
Essentials – £3.80/month (then £38): Multi-user, bills, time tracking, multi-currency
Plus – £5.60/month (then £56): Stock tracking, project profitability, budgeting
Advanced – £12.30/month (then £123): Up to 25 users, automation, batch invoicing, advanced reporting
90 per cent off for 12 months
Xero
Xero has several plans which businesses can choose from depending on their needs. The prices quoted are for standard packages (as at time of publishing) but the company has regular promotions and there are optional add-ons as well.
Plans and pricing (excl. VAT)
Simple – 70p per month for the first six months, then £7 per month: Quotes, MTD for ITSA, bank reconciliation, Hubdoc receipt capture
Ignite – £1.60 per month for the first six months, then £16 per month: All Simple features + enter bills, VAT filing to HMRC, optional bill payments and CIS returns
Grow – £3.70 per month for the first six months, then £37 per month: All Ignite features + pay up to 5 bills, expenses & mileage for 5 users (£2.50 per additional user), 5-person payroll, optional project tracking (£5 per user)
Comprehensive – £5 per month for the first six months, then £50 per month: All Grow features + bill payments for 10, multi-currency support, project tracking (for 10 users)
Ultimate – £6.50 per month for the first six months, then £65 per month: All Comprehensive features + bill payments for 15, advanced analytics, up to 10-person payroll, enhanced budgeting and insights
Intro offer: 90 per cent off for six months if you sign up by 30 January, 2026. Each package has a 30-day free trial.
See also: Making Tax Digital (MTD) – HRMC requirements and the best compatible software providers – After the rollout of Making Tax Digital (MTD) for VAT, MTD for Income Tax is being phased in from April 2026
Important self-assessment dates
Here are the need-to-know self-assessment dates throughout the year.
October 5: Deadline to register for self-assessment if you’re registering for the first time October 31: Self-assessment paper form deadline December 30: Self-assessment PAYE tax collection deadline January 31: Online self-assessment deadline; first ‘payment on account’ due (payment towards your next bill) April 5: End of the tax year; deadline to claim overpaid tax for previous years April 6: Start of the new tax year July 31: Second payment on account due
I’m still unsure about submitting my tax return – is there any support available?
If you have further questions, seek out advice from an accountant. The government also has a series of content to help you with your tax return, especially as a first-timer.
You can also check out Sage’s accounting software here.
Read more
Six reasons to tackle your self-assessment tax return early – Emily Coltman, chief accountant at FreeAgent, explores why it may be beneficial to take on the self-assessment tax return early
Should you register as a sole trader or a limited company? – Mart Abramov, CEO of TaxScouts, shares the positives and negatives of being a sole trader or a limited company, so you can make the best choice for your growing business
Best business bank accounts for sole traders – We’ve rounded up some of the best business bank accounts created with sole traders in mind
