Self Assessment Tax Return Checklist

If you need to file a Self Assessment tax return, having the right information ready before you start makes the process significantly faster and reduces the risk of errors.

This checklist covers everything you are likely to need, from personal details and income records to expenses, HMRC information and the deadlines you need to be aware of.

Who Needs to File a Self Assessment Tax Return?

Before working through the checklist, it is worth confirming whether you actually need to file.

You need to file a Self Assessment tax return if you are:

• Self-employed as a sole trader with income above a certain level
• A partner in a business partnership
• A company director
• An employee or pensioner with income over a certain threshold
• A landlord with income from renting out property
• Someone with income from savings, investments or dividends above your allowances
• Someone with foreign income
• Someone who needs to claim certain tax reliefs or repayments
• Someone who received a notice to file from HMRC

If you are not sure whether you need to file, contact HMRC or speak to an accountant. Filing when you do not need to is not harmful, but not filing when you should results in automatic penalties.

Key Dates to Know

Getting the dates right is the most important part of Self Assessment. Missing a deadline results in an automatic penalty from HMRC regardless of whether you owe any tax.

5 April End of the tax year. The tax year runs from 6 April to 5 April the following year.

6 April Start of the new tax year. You can begin preparing your return for the previous tax year from this date.

31 July Second payment on account deadline. If you make payments on account, the second payment for the current tax year is due by this date.

31 October Deadline for filing a paper Self Assessment tax return for the previous tax year.

31 January Deadline for filing your Self Assessment tax return online for the previous tax year. This is also the deadline for paying any tax owed and the first payment on account for the current year.

Most people file online. The 31 January deadline is the one to focus on.

Part 1: Your Personal Details

Start by making sure you have your basic personal information to hand.

Your details

• Full legal name
• Date of birth
• National Insurance number
• Unique Taxpayer Reference (UTR) number
• Home address
• Contact details

Your HMRC online account

• Government Gateway user ID and password
• Access to your HMRC online account if filing yourself

If you do not know your UTR number, it can be found on previous correspondence from HMRC, on previous tax returns or by logging into your HMRC online account. If you have never filed before, you need to register for Self Assessment first, which can take up to ten working days.

Part 2: Employment Income

If you were employed during the tax year, you will need details of your employment income.

For each employment during the tax year

• P60 certificate from your employer, showing total pay and tax deducted for the year
• P45 if you left a job during the tax year, showing pay and tax to the date you left
• P11D or P11D(b) if you received any benefits in kind from your employer, such as a company car, private medical insurance or other taxable benefits
• Details of any expenses you paid in connection with your employment that were not reimbursed by your employer

If you had more than one employer during the tax year, you will need a P60 or P45 for each.

Part 3: Self-Employment Income

If you were self-employed during the tax year, you will need your business income and expenses for the period.

Income

• Total income received from self-employment during the tax year
• Any invoices raised but not yet paid, if you use an accruals basis rather than cash basis

Expenses Self-employed people can deduct allowable business expenses from their income to reduce their taxable profit. Common allowable expenses include:

• Office costs including stationery and phone bills
• Travel costs including fuel, parking, train fares and hotel costs for business trips
• Clothing for work, such as a uniform or protective equipment
• Staff costs if you have employees
• Stock and materials used in your business
• Financial costs including bank charges and insurance
• Costs of business premises including rent, rates and utilities
• Advertising and marketing costs
• Professional fees including accountancy fees
• Training costs directly related to your current business

You cannot claim expenses that have a personal element, such as commuting costs, clothing that could be worn outside of work or personal phone calls.

Capital allowances If you purchased equipment, machinery or vehicles for business use during the year, you may be able to claim capital allowances rather than treating these as a straightforward expense. An accountant can advise on whether capital allowances apply to your purchases.

Using the cash basis or accruals basis Self-employed people can choose to record income and expenses either when money is actually received and paid (cash basis) or when it is earned and incurred (accruals basis). Make sure you know which basis you are using and apply it consistently.

Part 4: Property Income

If you received rental income during the tax year, you will need details of that income and the related expenses.

Income

• Total rent received from each property during the tax year
• Any other income received in connection with the property, such as charges for services

Expenses Landlords can deduct certain allowable expenses from rental income. These include:

• Letting agent fees and management fees
• Legal fees for lets of one year or less
• Accountancy fees
• Buildings and contents insurance
• Maintenance and repairs to the property, but not improvements
• Utility bills if paid by the landlord
• Ground rent and service charges
• Direct costs of letting the property such as advertising

Mortgage interest Landlords can no longer deduct mortgage interest directly from rental income. Instead, a tax credit equal to twenty percent of the mortgage interest paid is available. Make sure you have records of the interest paid on any buy-to-let mortgages during the year.

Furnished holiday lettings If you let a property as a furnished holiday let, different rules apply. An accountant can advise on the specific treatment.

Part 5: Savings and Investment Income

If you received income from savings or investments during the tax year, you may need to report it depending on the amounts involved.

Savings interest

• Total interest received from bank and building society accounts
• Interest from government gilts or corporate bonds
• Interest from peer-to-peer lending platforms

Most basic rate taxpayers have a Personal Savings Allowance that means some savings interest is tax-free. You may still need to report it if the total exceeds your allowance.

Dividends

• Total dividend income received from shares and investments
• Dividend statements or certificates from companies in which you hold shares
• Details of any dividends received from your own limited company

There is an annual dividend allowance. Dividends above this level are taxable at rates depending on your overall income.

Other investment income

• Income from unit trusts or investment funds
• Income from REITs or property funds

Part 6: Capital Gains

If you sold or disposed of assets during the tax year, you may have a capital gain to report.

Assets that may give rise to a capital gain

• Residential property that is not your main home
• Shares and investments held outside an ISA
• Business assets
• Other valuable items above a certain value

Information you will need for each disposal

• Description of the asset
• Date you acquired it
• Amount you paid for it, including any purchase costs
• Date you sold or disposed of it
• Amount you received, including any sale costs

There is an annual Capital Gains Tax exempt amount. Gains above this level are taxable. The rate depends on the type of asset and your level of income.

For residential property disposals, a separate capital gains tax return must be submitted to HMRC within sixty days of completion, with any tax due paid at the same time. This is separate from the Self Assessment return.

Part 7: Pension Contributions

If you made pension contributions during the tax year, you may be able to claim additional tax relief through your Self Assessment return.

Information you will need

• Total pension contributions made to personal or workplace pensions during the year
• Details of any employer contributions made on your behalf
• Confirmation of whether contributions were made on a relief at source basis or a net pay basis

Higher rate and additional rate taxpayers can claim additional relief on personal pension contributions through Self Assessment.

Part 8: Gift Aid Donations

If you made Gift Aid donations to charity during the tax year, you may be able to claim additional tax relief.

Information you will need

• Total Gift Aid donations made during the tax year
• Confirmation that you made a valid Gift Aid declaration for each donation

Higher rate and additional rate taxpayers can claim the difference between the basic rate tax relief already given to the charity and the higher rate of tax through their Self Assessment return.

Part 9: Other Income and Adjustments

Other income to include

• Income from a trust or settlement
• Foreign income of any kind
• Income from royalties or intellectual property
• Any other income not covered by the categories above

Adjustments and reliefs

• Trading losses from previous years that you wish to carry forward
• Enterprise Investment Scheme or Seed Enterprise Investment Scheme investments
• Venture Capital Trust investments
• Marriage Allowance transfers
• Blind Person's Allowance if applicable

Part 10: HMRC Correspondence and Previous Returns

Before filing your return, it is useful to have the following to hand.

• A copy of your previous year's tax return if available
• Any letters from HMRC received during the year
• Details of any payments already made to HMRC, including payments on account
• Details of any tax already deducted at source during the year

Common Mistakes to Avoid

Filing late The single most common and avoidable mistake. Set a reminder well before 31 January and do not leave it until the last week. HMRC's systems are frequently slow in January.

Missing income sources Make sure you account for all sources of income during the tax year, including small amounts of interest, occasional freelance work and any overseas income.

Claiming expenses you are not entitled to Only allowable business expenses can be deducted from self-employment income. Personal expenses, even if partially business-related, need to be apportioned correctly.

Not reporting the disposal of a residential property separately If you sold a residential property that is not your main home, you must submit a separate capital gains tax return and pay any tax within sixty days of completion. This is separate from the annual Self Assessment return and has its own deadline.

Not registering for Self Assessment in time If you need to file for the first time, you must register with HMRC before the deadline. Registration can take up to ten working days and must be done in advance of filing.

Do You Need Help With Your Self Assessment Return?

Self Assessment returns range from straightforward to genuinely complex, depending on your income sources, your expenses and your individual circumstances.

If your return is straightforward, this checklist should help you gather everything you need. If your return involves multiple income sources, property, capital gains, foreign income or significant business expenses, professional support will save you time, reduce the risk of errors and make sure you are not paying more tax than you need to.

Qestor Chartered Accountants helps individuals, sole traders, landlords, directors and contractors with Self Assessment tax returns across England and Wales. We review your income from all sources, apply the correct reliefs and allowances and submit your return to HMRC before the deadline.

Frequently Asked Questions

What is the deadline for filing a Self Assessment tax return?

The deadline for filing online is 31 January following the end of the tax year. Payment of any tax owed is also due by 31 January. Paper returns must be filed by 31 October.

What happens if I miss the Self Assessment deadline?

HMRC issues an automatic penalty of £100 for returns filed after the 31 January deadline, even if no tax is owed. Further penalties apply the longer the return remains outstanding.

Do I need to register for Self Assessment if it is my first time?

Yes. If you have not filed a Self Assessment return before, you must register with HMRC first. Registration can take up to ten working days, so do not leave it until January.

What is a Unique Taxpayer Reference?

Your UTR is a ten-digit number that identifies you to HMRC for Self Assessment purposes. It can be found on previous HMRC correspondence, on previous returns or by logging into your HMRC online account.

Can I claim my accountancy fees as an expense?

Yes. Accountancy fees incurred in connection with your self-employment or property rental business are allowable expenses and can be deducted from the relevant income on your Self Assessment return.