Intro – Self Assessment help Gravesend
Completing a Self Assessment tax return can feel complicated, particularly if you are filing for the first time. However, preparing the correct records and understanding each stage of the process can make it considerably easier.
In this guide, we explain how to fill in a Self Assessment tax return online, who needs to submit one, the information you will need and the common mistakes to avoid. We have also included the important deadlines for the 2025/26 tax year.
If your income or tax affairs are more complicated, King & Taylor can prepare and submit your return on your behalf. We are an established firm of chartered accountants based in Gravesend, supporting individuals, sole traders, landlords and business owners across Kent.
What is a self assessment tax return?
A self-assessment tax return is a form that you fill in and send to HMRC. The self-assessment tax return is used to report your income, calculate your tax and pay your tax.
If you’re self-employed or a company director, you have to fill in a Self Assessment tax return every year.
The tax return will ask how much money you earned during the year, and what you spent it on. HMRC will then use this information to work out how much tax you should have paid.
Who needs to submit a Self Assessment return?
You need to file a tax return if you are any of the following:
- Self-employed.
- A director of a company.
- Have rental income. This can include your home and other properties you let as well as letting out rooms within your own home (but not if you’re a lodger who pays rent to the homeowner). You may also have to pay tax on your profits from letting out holiday homes or caravans if they aren’t part of the lettings business itself.
- Have income from savings, shares or investments that are not taxed through an ISA or SIPP wrapper, such as stocks and shares held outside of these wrappers, unit trusts and open-ended investment companies that aren’t run by banks or building societies. These include overseas property investments (including UK residential property).
Have an annual income of £10,000 or more from savings, shares or investments. Have income from abroad. This can include rental income paid abroad. You may also need to fill in a tax return if you live outside the UK but work here and pay Class 1 National Insurance contributions (NICs), for example, if you’re a member of the armed forces based in Great Britain and pay Class 1 NICs under section 8 of the Social Security (Categorisation of Earners) Regulations
How can you submit your return? | Tax returns Kent
To submit your return, you can use one of the following methods:
- Online. You can submit your self assessment tax return online using HMRC’s online service. If you want to pay in instalments, use this method. You can also register for the service if you haven’t done so already.
- Paper form. If you prefer to fill out a paper form and post it yourself, download our self assessment tax return PDF (PDF). This document includes full instructions on how to complete each section of your return form – see ‘How do I complete my self assessment tax return?’ above for more information on completing each part of your submission. It is important that all sections are completed correctly as HMRC will reject any incomplete submissions or those with mistakes made in them – meaning that if this happens we won’t be able to process your claim until those sections have been completed satisfactorily
Step by step guide to filing your self assessment tax return
1. Sign in to your HMRC account
Visit GOV.UK and sign in using your Government Gateway details. If this is your first return, you will usually need to register for Self Assessment and obtain a ten-digit Unique Taxpayer Reference first.
2. Check your personal information
Make sure your name, address, National Insurance number and contact information are correct. You will also be asked questions that determine which sections of the return you need to complete.
3. Enter your employment income
If you were employed during the tax year, use the figures shown on your P60, P45 and any relevant P11D. Include every employment held during the year.
4. Report self-employed income
Enter your business turnover and allowable expenses. Depending on your circumstances, you may use either traditional accounting or the cash basis. Your records should support every figure entered. You can find out more info on expenses here – Claiming Tax Relief on Work-from-Home Expenses: What You Need to Know for 2026.
5. Declare other sources of income
This could include:
- Rental income
- Bank and building society interest
- Dividends
- Pension income
- Foreign income
- Capital gains
- Tips, commissions or casual earnings
6. Claim relevant tax relief
Include any eligible pension contributions, Gift Aid donations, business expenses and other reliefs. The relief available will depend on your individual circumstances.
7. Review your calculation
HMRC’s system will calculate an estimated amount owed based on the information entered. Check the calculation carefully, particularly any payments on account.
8. Submit the return
Confirm that the information is complete and accurate before submitting it. Save a copy of the return, tax calculation and submission receipt for your records.
By phone. If you have been sent an invitation to register for our self assessment tax return service, but you don’t want to use the online method, you can call us on the number below and we will be happy to help. By post. Alternatively, send your completed submission by post to: HM Revenue & Customs Self Assessment PO Box 2000 LIVERPOOL L75 1WX.
Self Assessment deadlines for 2025/26
If you need to complete a Self Assessment tax return for the 2025/26 tax year, which ran from 6 April 2025 to 5 April 2026, the main deadlines are:
- 5 October 2026: Deadline to register for Self Assessment if you are filing for the first time or need to register again.
- 31 October 2026: Deadline for submitting a paper tax return.
- 30 December 2026: Deadline for filing online if you want HMRC to collect tax owed through your PAYE tax code, where eligible.
- 31 January 2027: Deadline for submitting an online tax return and paying any tax owed for 2025/26.
- 31 January 2027: First payment on account for the 2026/27 tax year, if required.
- 31 July 2027: Second payment on account for the 2026/27 tax year, if required.
You can submit your return as soon as the tax year has ended. Filing early does not mean you have to pay immediately—the payment deadline will usually remain 31 January 2027. Completing your return early gives you more time to check the figures, understand how much you owe and budget for the payment. Self Assessment Deadlines 2026: Key UK Tax Dates You Need To Know.
If you miss the filing deadline, HMRC will normally issue an initial £100 penalty, even if you have no tax to pay. Additional penalties and interest may apply if your return or payment remains outstanding.
What income should you declare?
When completing your Self Assessment tax return, you must tell HMRC about all taxable income received during the relevant tax year, even if tax has already been deducted from some of it.
Depending on your circumstances, this may include:
- Employment income: Salary, wages, bonuses, commissions and taxable workplace benefits. You can usually find these figures on your P60, P45 or P11D.
- Self-employed income: Your total business turnover before expenses, including payments received for freelance work, contracting and side businesses.
- Property income: Rent received from residential property, commercial premises, holiday accommodation or letting a room in your home.
- Savings income: Taxable interest earned from bank accounts, building societies and other savings. Interest earned within an ISA is normally tax-free and does not need to be declared.
- Dividend income: Dividends received from UK or overseas companies, including dividends paid by a limited company you own. ISA dividends are normally excluded.
- Pension income: State Pension, workplace pensions, private pensions and certain taxable pension withdrawals.
- Foreign income: Overseas earnings, rental income, savings interest, dividends and pensions. Foreign income may still need to be reported even if tax was paid in another country.
- Capital gains: Profits from selling or disposing of taxable assets, such as shares, investment properties, cryptocurrency or valuable personal possessions.
- Other taxable income: This may include tips, commission, casual earnings, online selling profits, certain benefits, redundancy payments and income from a trust.
You should report your income accurately and keep supporting documents such as invoices, bank statements, payslips, dividend vouchers and property records. Some forms of income are covered by tax-free allowances or reliefs, but they may still need to be included on your return depending on the amount and your circumstances. You can read more about the current tax rates here.
If you are unsure whether a particular payment is taxable, speak to HMRC or a qualified accountant before submitting your return. Failing to declare taxable income can result in additional tax, interest and penalties.
How much time do I have to submit my return?
There is a deadline to submit your return or you may face a fine. You must submit your return by 31st January, if you are filing online, by post or via phone.
You can also submit it by email – but only if:
- You have received an error message from HMRC saying that you need to provide more information about your tax affairs – for example because you’ve missed one of their letters; or
- You have been told that your identity needs to be checked before they can accept your tax return.
What is a UTR number?
A UTR (Unique Taxpayer Reference) number is a unique number used to identify you and your business, as well as all their transactions with HMRC. You can find it on your tax notice or by logging in to GOV.UK to see your National Insurance number.
Each year, when you start a new job or set up a business, you’ll be given one of these numbers by the person responsible for paying your wages or making payments on your behalf (such as an employer). This means that they will know who they’re paying and keep track of any payments that go through them – so if there’s ever any question about whether money should have been paid out or not, it can be traced back quickly using this database.
If at some point during the year you have any dealings with HMRC (for example when filing self assessment), then this number will also be used so that everything matches up correctly between them and whoever made those payments originally – which again makes life easier for both sides!
How to find your UTR number if you don’t have one?
If you have not received a UTR number, contact HMRC.
You can find your UTR by looking at your last tax return, or any of the following documents:
- P45 (if you are being paid wages)
- P60 (if you are self-employed)
- P11D (if you are receiving pension income)
What are some of the common mistakes made when filing self-assessment tax returns in the UK?
Self-assessment tax returns are often difficult to file. There are many rules and regulations that need to be followed when completing a self-assessment tax return in the UK.
* Some common mistakes made when filing self-assessment tax returns in the UK are: • Incorrectly reporting income or expenses • Not reporting all of your income and expenses • Claiming wrong amounts on deductions or credits
Conclusion
We hope this article was helpful in your quest to file your UK self-assessment tax return. If you have any other questions, please contact our team at any time. We have a range of services at King and Talyor, including year-end accounts, tax returns, VAT Returns & Bookkeeping, Payroll and more. Read more about our services here. Please don’t hesitate to get in touch!
