What Do You Need for a Self Assessment Tax Return? A London Accountant’s Checklist for Sole Traders and Company Directors

Wix

Oct 1

7 min read

If you are searching for a self assessment tax return accountant London business owners can rely on, you are probably trying to file accurately, avoid last-minute stress and make sure nothing important is missed. Whether you are a sole trader or a company director with personal income to report, the quality of your records can make the whole process much easier.

At First Step Accounting Ltd, we support individuals and businesses from East Finchley, London, N2 0LP, with personal tax, income tax, tax returns, bookkeeping and wider business support. This practical checklist shows what to gather before your return is prepared, what people often forget, and when professional help can save time and reduce errors.

Self assessment tax return accountant London: why the right checklist matters

A Self Assessment return is not just a form to complete at the last minute. It brings together your income, expenses and supporting records for the tax year, and small gaps can lead to questions, amendments or a stressful rush before the deadline.

Having a clear checklist helps you:

find the right documents earlier
spot missing records before filing starts
separate business figures from personal items
give your accountant cleaner, more accurate information
understand where extra tax planning advice may be useful

If you want help with personal tax support or a practical review of your records, we can guide you through the process clearly.

Who should use this checklist?

This guide is especially useful if you are:

a sole trader preparing to report business profits
a company director who needs to file a personal tax return
someone with more than one income source
filing for the first time and unsure what HMRC will expect
catching up after a busy year and want a simple structure to follow

For many people, the difficulty is not the return itself. It is knowing which figures belong where and which documents should be ready before the work begins.

What you need before starting your Self Assessment tax return

1. Your personal tax references and HMRC details

Start with the basics. Your accountant will usually need your Unique Taxpayer Reference, National Insurance number and any recent HMRC correspondence linked to your Self Assessment record.

It also helps to keep a clear note of the tax year being prepared and whether anything significant changed during that period, such as starting self-employment, becoming a director, or taking on a new source of income.

2. Income records for sole traders

If you are a sole trader, your return depends on accurate income records. Do not rely on rough estimates or bank totals alone.

Useful documents often include:

sales invoices issued during the tax year
cash takings summaries where relevant
online platform or payment processor statements
bank statements showing business income received
records of unpaid invoices if your bookkeeping tracks them separately

Where bookkeeping is incomplete, it is often worth getting bookkeeping support before the return is finalised. Clean books usually make tax work faster and more reliable.

3. Expense records and proof of business costs

Expenses matter because your taxable profit is based on income less allowable business costs, not simply the money left in the bank. Good records help ensure your return reflects the business properly.

Depending on how you work, you may need:

receipts and bills for business purchases
software and subscription costs
phone, internet and office costs used for business
travel records and supporting receipts
professional fees and insurance documents
evidence for equipment or other larger purchases

Keep personal spending separate wherever possible. Mixed records often create avoidable questions later.

4. Bank, card and bookkeeping records

Even where you keep invoices and receipts, your bank and card records still matter. They help confirm what was paid, when it was paid and whether the bookkeeping matches the underlying transactions.

Before your return is prepared, gather:

business bank statements
business card statements
bookkeeping reports for the tax year
details of any cash introduced to or taken from the business
notes on unusual transactions that need explanation

This is one reason many clients ask us for tax returns help alongside bookkeeping and wider accounts support.

5. Extra records company directors often need

If you are a company director filing a personal return, the paperwork is often broader than for a sole trader. You may need to bring together salary, dividends and other personal income sources so the return reflects the full picture.

Common director records include:

P60 or other payroll summaries
dividend vouchers or a clear dividend schedule
details of expenses reimbursed by the company
benefits information where relevant
director's loan information if personal and company finances have overlapped
savings interest, rental income or investment records if applicable

Directors often benefit from business tax advice as well as personal tax support, especially when company and personal decisions affect each other.

Documents people often forget to include

Some of the most common delays happen because one smaller category of income or relief is missed. Before sending records across, check whether any of the following apply to you:

bank or building society interest
dividend income outside your main company records
rental income and related property paperwork
pension contribution records
Gift Aid donation records
employment documents from another role
paperwork relating to asset sales or capital gains

You do not need every item on this list. The point is to review your year properly rather than focus only on your main trading income.

Common mistakes that make Self Assessment harder than it needs to be

Most filing problems start long before the return is submitted. They begin with missing paperwork, unclear bookkeeping or assumptions that can no longer be backed up.

Waiting too long: leaving everything until the deadline reduces time for checks and questions.
Guessing figures: estimated numbers can create avoidable amendments later.
Mixing personal and business spending: this makes it harder to identify allowable costs clearly.
Forgetting extra income sources: salary, dividends, savings interest or property income may all matter.
Sending incomplete records: missing statements or receipts slow the process down.
Skipping advice after a major change: a new business structure, new investments or changes in drawings can all affect the return.

A checklist is useful, but it is even more valuable when someone experienced reviews your records before submission.

When it makes sense to use an accountant

Some people have straightforward returns and well-organised records. Others have a combination of business activity, director income and personal tax issues that deserve a closer look.

Using an accountant is especially sensible if:

this is your first Self Assessment return
you are both a sole trader and a company director
your bookkeeping is behind or inconsistent
you have several income sources to report
you want support with compliance and year-round tax planning, not just form filling

At First Step Accounting Ltd, we can help with personal tax, income tax, bookkeeping, VAT returns, management accounts and wider accounting support, so your tax return is looked at in the context of the bigger financial picture.

How we support Self Assessment clients at First Step Accounting Ltd

We are based in East Finchley, London, N2 0LP, and support businesses and individuals across London and the UK. Our services include personal tax, tax returns, bookkeeping, payroll, VAT returns, management accounts, year-end accounts and business advice.

Clients often come to us because they want clear communication, practical support and a structured process rather than last-minute confusion. We also offer a free consultation, with a free 2 to 3 hour in-depth initial assessment available to understand your needs properly. Remote accounting services are also available nationwide.

First Step Accounting Ltd was established in 2020. We are connected with the Association of Accounting Technicians, and our credentials include MAAT AATQB accreditation and AAT qualifications in accounting, bookkeeping, tax and taxation ethics.

If you want one place to start, our website is the best route for Self Assessment and tax return support.

Frequently asked questions

What do I need to give an accountant for a Self Assessment tax return?

You will normally need your tax references, income records, expense evidence, bank or card statements and details of any other personal income. If you are a company director, include salary, dividend and company-related records that affect your personal tax position.

Do company directors always need to file a Self Assessment tax return?

Not simply because they are directors in every case. However, if HMRC has asked you to file, or you have personal income that needs to be reported, you should get organised early and take advice if you are unsure.

Can a sole trader prepare a Self Assessment return without bookkeeping software?

It is possible to keep records in different ways, but accuracy is what matters most. Your income and expenses should be complete, organised and supported by proper evidence so the figures can be prepared with confidence.

How early should I start preparing my Self Assessment records?

As early as possible. The earlier you review your records, the more time there is to identify gaps, answer questions and deal with anything unusual before filing deadlines become urgent.

What if I have both business income and other personal income?

That is exactly when a checklist helps. Your return may need to bring together different sources, so it is important to gather everything in one place and make sure no part of the picture is overlooked.

Need help with your Self Assessment tax return?

If you want a self assessment tax return accountant London sole traders and company directors can speak to with confidence, we are here to help. At First Step Accounting Ltd, we take a practical, supportive approach and help you get your records in order before filing becomes a last-minute problem.

Contact us for a free consultation to discuss your Self Assessment tax return. You can reach us via our website, email us at office@firststepaccounting.co.uk, or call 07453 993955 to arrange a conversation.

Getting the checklist right now can save time, reduce stress and put you in a stronger position for the rest of the tax year.