The smoother your Self Assessment return goes, the earlier you gather the right paperwork. This checklist covers the information an accountant typically needs. Exactly what applies depends on your circumstances, so treat it as a starting point rather than a definitive list.

Your personal and tax details

To file on your behalf, your accountant will need some basics:

  • Your National Insurance number
  • Your Unique Taxpayer Reference (UTR), the ten-digit number HMRC issues when you register for Self Assessment
  • Contact details and, where relevant, authorisation for the accountant to deal with HMRC on your behalf
  • Details of your bank account (used for any repayment due to you)

If this is your first return, you may need to register for Self Assessment first; GOV.UK explains how and the deadline for doing so.

Income from self-employment

If you are self-employed or a sole trader, your accountant needs a complete picture of your business income and costs:

  • Total sales or turnover for the tax year
  • Business expenses, categorised: for example materials, travel, use of home, insurance, subscriptions and professional fees
  • Records of any assets purchased for the business
  • Your bookkeeping records or accounting software access

Keeping contemporaneous records throughout the year makes this far easier than reconstructing figures in January.

Employment income

If you were also employed during the year, provide:

  • Your P60 (end-of-year summary of pay and tax) from each employer
  • Your P45 if you left a job during the year
  • Your P11D if you received taxable benefits such as a company car or private medical cover

Other income to declare

Self Assessment covers more than just self-employment. Tell your accountant about:

  • Rental income from property, with the associated allowable expenses
  • Dividends and interest from savings and investments
  • Pension income and any state benefits that are taxable
  • Capital gains from selling assets such as shares or a second property
  • Any foreign income
  • Income from side activities, online selling or the “gig economy” where it is taxable

Payments and reliefs that reduce your bill

Just as important as income is anything that reduces your tax or has already been paid:

  • Pension contributions you made personally
  • Gift Aid donations to charity
  • Student loan repayment details
  • Any payments on account already made towards this year’s bill
  • Details relevant to the High Income Child Benefit Charge, if it applies to your household

Bringing it together

The single biggest thing you can do to make your return painless is to keep organised records year-round rather than scrambling before the deadline. Cloud bookkeeping, a dedicated business bank account and a simple habit of filing receipts as you go all reduce the last-minute rush, and reduce the chance of missing an expense or relief that would lower your bill.

If anything on this list is unclear or you are not sure whether it applies to you, it is better to raise it early. Your accountant would far rather answer a question in autumn than discover a gap the night before filing.

How we can help

We prepare, check and file Self Assessment returns for sole traders, landlords, company directors and individuals with more complex tax affairs. See our Self Assessment service, or request a quote and we will send you a tailored list of exactly what we need from you.