When it comes to Self Assessment tax returns, even the most organised business owners and professionals can feel overwhelmed. Deadlines creep up, paperwork piles up, and tax rules change just enough to cause confusion.
This two-part guide will walk you through how to file your tax return with confidence — covering who needs to file, what to gather before you start, how to avoid penalties, and key allowances that could save you money.
In Part 1, we focus on who needs to file and how to prepare your documents efficiently.
Who Needs to File a Self Assessment Return?
Not everyone in the UK needs to complete a Self Assessment tax return, but you must file one if any of the following apply:
- You’re self-employed or a partner in a partnership
- You received untaxed income such as rental income, dividends, savings interest above the allowance, foreign income, or capital gains
- You or your partner received Child Benefit and either of you had an adjusted net income over £60,000, triggering the High-Income Child Benefit Charge (HICBC)
Important change for PAYE-only high earners:
From 2024/25, HMRC has removed the rule that required high-income PAYE employees to file just because of income level. If all your income is taxed at source and you have no additional income, you may no longer need to file — but if you receive dividends, rent, or capital gains, filing could still apply.
Always check HMRC’s online tool to confirm your filing requirement.
What to Gather Before You Start
Before logging into your tax return, save time and stress by gathering everything you’ll need in one place — either digitally or in a physical folder.
Employment
- P60, P45 (if applicable), P11D (benefits), or employer-provided benefit summaries
Self-Employment
- Income and expense records, invoices, bank statements, and mileage logs
- Note: From 2024/25, the cash basis is the default for unincorporated businesses unless you elect to use accruals
Property Income
- Rental statements, mortgage interest, agent fees, repair costs, and property sale details
Savings and Investments
- Bank interest, dividend statements, and investment income records
Capital Gains
- Purchase and sale dates, costs, contract notes, and details of any property disposals
Pensions and Charitable Giving
- Pension contributions (grossed-up values) and Gift Aid donation totals for additional relief claims
Other Key Areas
- Student loan details
- Child Benefit amounts
- Cryptoasset transactions (staking, mining, or sales) — note: new HMRC reporting rules begin in January 2026
Keep all records for at least five years after the 31 January deadline.
Organise as You Go
Throughout the year, set up a dedicated folder or cloud drive for all tax-related paperwork. Store copies of invoices, pension statements, and donation receipts as they come in — it will make filing far easier and help prevent missed deductions.
Up Next in Part 2:
In the second part of this guide, we’ll walk through how to complete your Self Assessment online, avoid penalties, and make the most of allowances and reliefs to reduce your tax bill.
In the meantime, if you’d like a review of your draft return or professional help preparing and filing, we’re here to help ensure your Self Assessment is accurate, compliant, and on time. Get in touch!
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