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Self Assessment Tax Return Service

We handle everything from calculation to HMRC submission, so you stay compliant and avoid penalties.

  • Fixed fee pricing with no hidden costs
  • Accurate calculations and on-time HMRC submission
  • Expert support to reduce errors, penalties and missed deadlines
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Self Employed Tax Returns and Self Assessment Filing Fees

Our self assessment tax return service is priced clearly with no hidden fees or unexpected extras. You’ll know exactly what you’re paying upfront, with preparation and HMRC submission handled by experienced UK accountants.
£275 + VAT

What this means for you

Fixed fee self assessment tax return
One clear, upfront price
No hourly billing or surprise charges
HMRC-compliant calculations and submission
Expert support throughout the process
If your tax affairs are more complex, such as multiple income sources, we’ll confirm any additional costs upfront before proceeding.

Experience the difference with expert self-assessment

How Our Self Assessment Service Works

Our self assessment tax return service follows a clear, structured process designed to keep everything accurate, compliant, and on time.
Share your documents securely
Upload your income details, expense records, and any relevant tax information through our secure online portal. We’ll confirm exactly what’s needed so nothing is missed.
We prepare your return
Your dedicated accountant reviews your information, calculates your tax position, and prepares your Self Assessment in line with current HMRC rules.
You review and approve
Before anything is submitted, we send your completed return for review. You can ask questions, request clarification, and approve once you’re comfortable everything is correct.
We submit to HMRC
As your registered agent, we file your return directly with HMRC through our secure agent services account. You receive confirmation as soon as it has been successfully submitted.
We confirm payment deadlines
After submission, we clearly outline your tax liability, payment dates, and any payments on account due. This ensures you stay ahead of HMRC deadlines and avoid penalties.

See why thousands choose Sleek for Self Assessment Tax Return Services

Swift setup

Getting started is quick and straightforward. Share your details securely online and we’ll take it from there. No piles of paperwork, no back and forth.

Clear, fixed pricing

You’ll know the cost upfront. Our self assessment tax return service comes with a fixed fee, so there are no hidden extras or surprise charges later on.

Efficient, cloud-based process

We use secure, MTD-compliant, cloud accounting tools like Xero to streamline your self assessment. That means faster turnaround times, accurate figures, and everything kept safely in one place.

HMRC registered agent

As an HMRC registered agent, we can file and manage your return directly through our agent services account. This means seamless communication with HMRC and complete oversight of your submission.

Peace of mind with HMRC

Your return is prepared and submitted by experienced UK accountants. We deal with HMRC on your behalf, so you don’t have to worry about deadlines, errors, or penalties.

Who needs to submit a self assessment tax return?

Self-employed or a sole trader earning over £1,000
A company director or business owner with untaxed income
A landlord with UK or overseas rental income
A contractor under the CIS scheme
Earning untaxed income such as dividends, interest or freelance income
A higher earner claiming Child Benefit with income over £50,000

Meet Sleek’s lovely accounting team

Our Self Assessment accountants support sole traders, landlords and company directors with accurate tax returns, HMRC compliance and clear advice, ensuring everything is filed correctly and on time. With over 170 years of combined experience and qualifications including ACCA, CIMA, AAT and ICAEW, our UK team provides expert support across Self Assessment, tax planning and ongoing compliance.

Ready to get your self assessment tax return sorted?

Filling your self assessment doesn’t need to be stressful. Our expert accountants handle everything, from calculations to HRMC submission, so you can relax knowing it’s done right and on time.

Helpful accounting guides for UK business owners

FAQs on self assessment tax returns

What is a self assessment tax return?

A self assessment tax return is how you report your income to HMRC when tax isn’t fully deducted through PAYE. It involves declaring income, expenses, and any other taxable gains for the tax year. 

HMRC then calculates how much tax you owe or whether you’re due a refund. It must be submitted accurately and on time to avoid HMRC or Companies House penalties.

If you need more information on how to register for Self Assessment with HMRC, check out our guide.

Who needs to submit a self assessment tax return?

You’ll usually need to file a self assessment tax return if you’re self employed, a company director, a landlord, or receive untaxed income. It can also apply if you earn over certain thresholds, claim child benefit on a high income, or have capital gains to report. If HMRC can’t tax you automatically, self assessment is required.

What happens if I file my self assessment late or incorrectly?

Filing late or submitting incorrect information can lead to automatic penalties, interest charges, and follow-up from HMRC. Even small mistakes can trigger fines or investigations. Using a professional self assessment tax return service helps ensure your return is accurate, complete, and submitted on time, reducing the risk of unnecessary penalties or stress.

What income do I need to include on my tax return?

Your self assessment tax return must include all taxable income for the year. This can include self employed income, dividends, rental income, freelance work, interest, and certain benefits. You’ll also need to report any capital gains. Including everything correctly is essential, as missing income can lead to penalties or amended tax bills.

Can you deal with HMRC on my behalf?

Yes. When you use our self assessment tax return service, we can act as your agent and liaise with HMRC for you. This means we handle submissions, respond to queries, and help resolve issues if HMRC needs clarification. It saves you time and removes the pressure of dealing with HMRC directly.

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How much does a self assessment tax return cost?

Our self assessment tax return service starts from a fixed fee of £275 plus VAT for a standard return. This includes preparation, review, and submission to HMRC. If your tax affairs are more complex, we’ll always explain any additional costs upfront before starting, so you know exactly what to expect.

What information do I need to provide for self-employed tax services?

You’ll need to share details of your income, expenses, and any other relevant financial information for the tax year. This may include invoices, bank statements, dividend records, or rental income details. We’ll guide you on exactly what’s needed and keep the process simple, so nothing important is missed.

Need more information?

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