Your Self Assessment tax return, filed by a UK accountant

Prepared, checked and submitted to HMRC on time, from £275 + VAT.

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Why file your Self Assessment with Sleek

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A real accountant files your return

Not a form to fill in yourself. A qualified UK accountant prepares your return and you deal with them directly.

AI does the legwork, an accountant signs off

You get the speed and accuracy of automation, with a qualified person accountable for every figure filed.

Every relief you are owed, claimed

Pension relief, Gift Aid, mileage, use of home: the claims people often miss when they file on their own.

Filed on time, no penalties

We track your deadline and file early, so you avoid the £100 late penalty and the stress of the January rush.

Self Assessment pricing

Switch to Sleek and ‎‎ save 20% on annual accounting, with reliable support and full compliance.

Self Employed Tax Returns and Self Assessment Filing Fees

£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

What's included in your Self Assessment

Your return, prepared and filed

We complete every section that applies to you and submit it directly to HMRC.

All your income, in one return

Employment, self-employment, rent, dividends, interest and more, pulled together correctly.

Expenses and reliefs claimed

Allowable costs, pension relief, Gift Aid and marriage allowance, all checked and applied.

Your tax bill, explained

What you owe and when, including payments on account, so nothing lands as a shock.

Capital gains, if any

Gains on property, shares or crypto worked out and reported in the right place.

A check for next year

Where you could pay less next time, and whether you still need to file at all.

Looking to know more?

Meet the accountants who file your return

Toby Denwood (ATT)

Tax Manager

Toby heads our UK tax team, advising owner-managed businesses on Corporation Tax, personal tax and compliance obligations.

Chloe Waite (MAAT, ACCA)

Accounts Manager

Chloe supports a wide range of Sleek clients with year-end accounts, VAT returns and Self Assessment.

Holly Chapman (MAAT)

Senior Accountant

Holly specialises in year-end accounts and management reporting for UK businesses.

Noorahmad Khan (ACCA)

Account Manager

Noorahmad is an ACCA-qualified accounts manager with over a decade of experience, specialising in year-end accounts and financial reporting.

Nuzhat Haider (ACCA)

Senior Accounting Manager

Nuzhat supports SMEs and e-commerce businesses with statutory accounts, Corporation Tax and VAT compliance.

How it works

Tell us about your income

You

Share where your income comes from

Sleek

A fixed price for your return, not a range

Send us your figures

You

Upload what you have, we chase the rest

Sleek

We authorise with HMRC and gather your records

We prepare and you approve

You

Review the return and the tax owed

Sleek

We draft it, claim every relief and explain the bill

We file with HMRC

You

Give the go-ahead

Sleek

Submitted on time, confirmation sent to you

Ready to get your return done?

Helpful guides on Self Assessment

How to file a Self Assessment tax return

The steps from start to submission, the information you need and the deadlines that matter.

How to register for Self Assessment

Who needs to register, the 5 October deadline and how to get your UTR in time to file.

Self Assessment expenses you can claim

The costs you can put through your return, what you can’t, and the records HMRC expects.

FAQs on Self Assessment tax returns

Do I need to file a Self Assessment tax return?

You usually need to file if you were self-employed and earned more than £1,000, rented out property, had untaxed income from dividends or interest, made capital gains, or earned over £60,000 and claim Child Benefit. If you are not sure, tell us about your income and we’ll confirm whether you need to file before you pay anything.

Do you use AI to prepare my tax return?

Yes, for sorting your figures, matching records and flagging anything that looks incomplete. A qualified UK accountant then reviews the whole return and signs it off before it is filed. The automation makes the work faster; the responsibility for your return sits with a real person.

When is the Self Assessment deadline?

For an online return, the deadline is 31 January after the end of the tax year, and any tax you owe is due by the same date. If you need to register for Self Assessment, do it by 5 October. We track your dates for you and aim to file well before January so there is no last-minute rush.

What happens if I file my tax return late?

HMRC charges an automatic £100 penalty the day after the deadline, even if you have no tax to pay. After that, daily penalties, further fixed charges and interest can build up to well over £1,000. Filing on time is the simplest way to avoid all of it, which is exactly what we handle.

What are payments on account?

If your tax bill is over £1,000, HMRC usually asks you to pay next year’s tax in two advance instalments, due on 31 January and 31 July. It can feel like being billed twice the first time it happens. We work out what is due and when, and explain it clearly so it never catches you out.

How much does it cost to file a Self Assessment with Sleek?

From £275 + VAT, as one fixed price. What you pay depends on how complex your return is, for example whether you have self-employment, rental income or capital gains. You get the price before you commit, and we don’t bill by the hour.

Need more information?

Browse our articles for in-depth guides, expert tips, and the latest updates on UK business essentials.

Carles M,
Sleek Advisor

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