Self-assessment checklist (UK)

Self-assessment doesn’t have to be a January panic. If you gather the right information steadily (and keep it in one place), your return becomes a tidy annual task.

Use this checklist to prepare what’s needed for your self-assessment return before you (or your accountant) start the final calculation.

Who this is for

• Sole traders and partners
• Landlords with rental income
• Directors who need to report dividends and other personal income
• Anyone who files a self-assessment return with HMRC

Quick deadline reminders (general)

• Online self-assessment returns are commonly due by 31 January after the tax year end.
• Paper returns are commonly due earlier (often 31 October).
• Many people also have payments on account (often due 31 January and 31 July).

Deadlines and rules can vary, so treat these as a prompt and confirm what applies to you.

Checklist: personal and HMRC details

• Your National Insurance number
• Your Unique Taxpayer Reference (UTR)
• Your Government Gateway / HMRC login details (kept securely)
• Details of any changes of address during the year
• Your employment status changes (new job, stopped working, started self-employment)

Checklist: self-employed / business income

Bring together:

• Sales invoices or income summaries (by month is ideal)
• Online platform statements (if relevant)
• Cash income records (if applicable)
• Any other business income (grants, commissions, etc.)

If you’re not sure what counts as business income, note it down anyway. It’s easier to review with a clear trail than to recreate it later.

Checklist: allowable business expenses (records + totals)

For each expense category, keep evidence (invoice/receipt) and a total:

• Materials / stock
• Subcontractor costs (if applicable)
• Motor costs or mileage logs (be consistent)
• Tools, equipment, and subscriptions
• Phone and internet (note the business-use percentage if mixed)
• Travel (what/why/where)
• Professional fees (accountancy, software)
• Insurance
• Use of home as office (how you calculated it)

Practical tip: make a quick note for any “odd” expense. Context now saves time later.

Checklist: employment income (if you had a job)

• P60 (end-of-year summary)
• P45 (if you changed jobs)
• Any P11D benefits information (if relevant)
• Pay slips if anything looks unusual

Checklist: other income sources

Gather what applies to you:

• Dividends (voucher/statement)
• Bank interest and savings income
• Rental income (rent received, agent statements, and allowable costs)
• Pension income statements
• Capital gains information (sale of shares, property, crypto activity, etc.)
• Any foreign income documents

If you have multiple income streams, a one-page list of “what I earned and where it came from” is surprisingly helpful.

Checklist: pension contributions and reliefs

• Personal pension contributions (statements)
• Gift Aid donations
• Student loan details (plan type and what you’ve paid)
• Child Benefit information (if relevant)

Checklist: what to prepare if you’re a subcontractor (CIS)

• CIS statements showing tax deducted at source
• Your gross payments and deductions totals
• Notes on any missing statements (who/when)

CIS often creates confusion because you may have tax withheld already. Keeping clean CIS records prevents double-counting and missed relief.

Simple review checks before submission

• Does your profit figure look reasonable compared to last year?
• Are there any months missing from income or expenses?
• Any big one-offs (equipment purchase, refund, insurance claim) noted clearly?
• Is your business/personal split documented where needed?

Disclaimer

This checklist is general information, not personal tax advice. Your exact requirements depend on your circumstances and HMRC rules can change. If you’re unsure what to include, get tailored advice before filing.

Want help keeping things simple? Jeremy can set up a straightforward monthly routine so your next return is built from clean records, not guesswork.