Preparing for your Self Assessment can feel overwhelming. Many individuals and business owners delay the process due to uncertainty about what they need to provide. Inaccurate or incomplete information often leads to delays, penalties, or miscalculated liabilities. Luckily, for those who can afford it, there's another option: hire an accountant.
This guide walks you through what you might need to give your accountant for Self Assessment in the UK, helping you stay compliant and avoid penalties. Read on for a structured checklist covering all the expected information and documents you might need to supply your accountant.
What Information Should I Give My Accountant for Self Assessment?
If you plan on hiring help with your taxes, you might be thinking: “What do I need to give my accountant for Self Assessment?” In the UK, accountants filing Self Assessment are doing so on your behalf. Therefore, you should expect to at least share the same data which you would use if filing Self Assessment yourself.
For an accountant to complete your Self Assessment correctly and on time, therefore, you will need to provide accurate and complete information about your income. Providing the correct documents and details ensures:
- Timely filing
- Accurate tax liability calculations
- A reduced risk of investigation from HMRC
- The most efficient use of your accountant’s time
Remember that HMRC places the responsibility on you (the taxpayer) for any errors in your Self Assessment – even if you hired an agent (your accountant). Since they are submitting to HMRC on behalf of you, it is your responsibility to check that what they're doing is correct, using the information you provide them.
Not only is it essential for the accountant to receive the correct information to do their work, but it is vital for you to provide it in good time and to communicate effectively. Next, let’s look at a breakdown of the kind of information which might be expected.
Personal Information for Self Assessment
You should expect to give your accountant personal identification details for Self Assessment. This typically includes the following:
- Full name and current address
- Contact details (email address and phone number)
- Unique Taxpayer Reference (UTR) number
- National Insurance (NI) number
Income Documents to Provide for Self Assessment
After confirming your identity with the necessary details, you should now provide the main Self Assessment information: your income. Self Assessment covers personal income across a wide range of potential income streams. To calculate your total taxable income, and finally your tax liability, you must disclose anything which might be considered relevant.
If in doubt, it is usually better to mention a potentially relevant income to your accountant; if it is not relevant, then they can simply omit it. However, if you fail to mention a taxable income stream, your accountant will be unable to help you to avoid repercussions later. Read on to compare some of the income streams you might need to declare:
Employment Income Documents
If you are employed in traditional employment (e.g. as opposed to self-employment), or if you were an employee during the tax year:
- P60 – showing total income and tax paid for the tax year
- P45 – for any jobs you left during the tax year (listing any tax paid)
- P11D – describing any “benefits in kind” (e.g. a company car or interest-free loan)
Note that you should count any full-time, part-time or casual employment here. This can include:
- Income as a company director
- Agency work
- Foreign employment income (received as a UK resident)
Self-Employment Income Documents
If self-employed, you should expect to give your accountant copies of:
- Invoices (both issued and received)
- Receipts for any eligible business expenses
- Relevant bank statements
- Bookkeeping records (typically digital records, as per HMRC recommendations)
- Summaries of income/expenses by category (providing your accountant with the bigger picture)
Rental Income for Landlords (UK Property)
For any rental properties, try to provide:
- Lease/letting contracts
- Relevant bank statements (e.g. showing rental income/expenses)
- Property-related documents (e.g. demonstrating your ownership or mortgage status)
- Invoices relating to your UK property (e.g. rental income)
- Expenses (e.g. repair costs, council tax, fees, mortgage interest)
Investment and Dividend Income
Include essential information such as:
- Dividend vouchers
- Annual investment summaries (e.g. from NS&I accounts)
- Interest certificates from UK savings or investments
Note that you do not need to include interest from any Individual Savings Accounts (ISAs) here, but it would likely be useful to disclose these to your accountant anyway.
Other Income Sources
Other reportable income can include:
- Partnership income
- Capital gains
- State and private pensions (annual statements)
- Foreign income (with currency conversions)
Business Expenses for Self Assessment
If you’re a sole trader (self-employed), it’s important to keep track of expenses – some of which might be eligible for tax relief. Try to give your accountant evidence such as:
- Purchase receipts or invoices for your business
- Office expenses (e.g. stationery, printing costs, rent for premises)
- Public transport expenses from business travel
- Car mileage or fuel expenses
- Accommodation or subsistence expenses from business travel
- Subscription fees for professional/trade bodies
- Website costs or software subscription receipts
Capital Gains Tax Documents
If you have disposed of assets during the relevant tax year, provide:
- Asset type and details (property documentation, share certificates, etc.)
- Accurate dates of purchases and disposals
- Evidence of purchase and sale prices
- Proof of any related legal costs
- Receipts for estate agent or auctioneer fees
Pension Contributions and Self Assessment
In your Self Assessment, certain pension scheme contributions might be tax-free. For your accountant to help you claim tax relief on pension contributions, try to share:
- Annual pension contribution statements
- Details of employer and personal contributions
- Details of any private pension schemes
- End-of-year certificates (P60) from pension providers
- Evidence of Additional Voluntary Contributions (AVCs)
Records of Charitable Donations
Donations to registered UK charities under Gift Aid qualify for tax relief. In addition to last year’s charitable donations, you may also be able to include donations made in the current tax year. Provide:
- Any copies of Gift Aid declaration forms
- Receipts for your charitable donations
Loan and Mortgage Interest for Tax Relief
Part of Self Assessment can involve personal loans and mortgages. Interest on certain types of loans may be eligible for tax relief. Give the following details to your accountant, if applicable:
- Certificate(s) of Interest (from mortgages)
- Business-related loan agreements (e.g. from your sole trading or as a landlord)
- Student Loans Company (SLC) statements (for repayments through Self Assessment)
Claiming Tax Relief and Allowances
If you wish to claim personal allowances or deductions, provide your accountant with:
- Records of Marriage Allowance transfer
- Certificate indicating eligibility for Blind Person’s Allowance
- Records of professional or trade-related subscriptions
- Any other eligible business expenses (see our comprehensive guide)
Previous Year’s Self Assessment Tax Return
You may wish to provide a detailed copy of your previous Self Assessment return. This can help your accountant by providing context and aiding consistency. This is especially relevant if you have not filed your Self Assessment via the same accountant before.
What Happens If You Don’t Have the Right Documents?
Failing to give your accountant the necessary documents for Self Assessment can lead to:
- Delays in filing your tax return
- Inaccurate tax calculations
- Investigation or penalties from HMRC
- Overlooked tax reliefs or allowances
If you are disorganised, your accountant's fees may increase due to the extra time spent sourcing/verifying missing data.
Conclusion
In this article, we have detailed what you may need to give your accountant for Self Assessment in the UK. Provided that you share the right documents, your accountant should be able to ensure a smooth and accurate Self Assessment return. Feel free to use the checklist above as a guide to stay organised and compliant!
If you wish to avoid fees and streamline your Self Assessment, register with AbraTax instead.