Taxfix vs HMRC Self Assessment: what’s the difference?

Taxfix doesn’t replace HMRC. Think of us as the people who do the paperwork: an accountant prepares your return, and nothing goes to HMRC until you’ve approved it.

We’re a paid service, so here’s the trade-off. HMRC’s online route is free, but you fill in every form yourself. With Taxfix, you pay a fixed fee and an accountant does that work for you.

Key takeaways

• HMRC is the tax authority, and Self Assessment is the return you send to it.
• Taxfix prepares your return with an accountant and files it with HMRC once you’ve approved it.
• With Taxfix, you pay a fixed fee instead of doing the forms yourself, and you can get tax advice from an accountant.
• Prefer to do it yourself? HMRC’s online service is free to use.

What is HMRC?

HMRC stands for HM Revenue and Customs. It’s the UK’s tax, payments and customs authority. In short, it collects the money that pays for public services. It also gives targeted financial support to families and individuals, and it values property to help work out tax and benefits.

Which taxes does HMRC collect?

HMRC collects several taxes, including:

• Income Tax
• Capital Gains Tax
• Inheritance Tax
• Corporation Tax
• VAT
• National Insurance

Income Tax and Capital Gains Tax are the ones most relevant to Self Assessment tax returns.

Does your tax return end up with them?

Yes. HMRC collects tax, so it also receives the tax returns that go with it. No matter who prepares your tax return, it ends up with HMRC.

What is Taxfix?

Taxfix is a paid tax platform, separate from HMRC. It connects people with UK tax accountants and digital tools, so their returns can be prepared and filed with HMRC.

How Taxfix works

Taxfix UK offers services for tax returns, tax advice, company tax returns, bookkeeping and Making Tax Digital for Income Tax (MTD). You can access them through the Taxfix app and platform.

What else does Taxfix offer?

Taxfix also offers tax advice from an accountant, to help you understand your tax position. You can choose the tax return service, the tax advice service, or both together in one bundle.

What Taxfix does not do

Taxfix does not replace HMRC or your obligation to register for Self Assessment. It also does not work out your tax bill. HMRC does that. Taxfix does not file your return until you have confirmed the information you provided.

Is Taxfix an alternative to HMRC?

There is no alternative to HMRC as the tax authority, because every UK Self Assessment return is submitted to HMRC. You can file yourself through HMRC’s free online service, or use a paid service such as Taxfix that prepares and submits the return for you.

Option	What it is	Cost	What you do
HMRC online	Online service for filing your return	Free	You prepare and submit the return yourself
Taxfix	Return prepared by an accountant	Fixed fee	You upload your documents and approve the return before it is filed
Traditional accountant	An ongoing relationship with one accountant	Varies, so check fees before you agree	Depends on your agreement with the accountant

Who needs to file a Self Assessment?

If you’re an employee with only a salary, you usually don’t need to file. Your tax is taken from your pay through PAYE.

These groups often need to file too:

• Self-employed: register if your gross self-employment income is over £1,000.
• CIS (construction workers): you may still need to file.
• First-time filers: register before you send your first return.
• High earners: if you had to pay the High Income Child Benefit Charge and did not pay it through PAYE, you must file.
• Investors (crypto, stocks, property): you must report gains above £3,000 (2026/27).
• Landlords: if your gross rental income is over £1,000, contact HMRC. If it is over £2,500, register.
• Expats and non-residents: your residence status changes what you report.
• Couriers, riders or drivers: if you’re self-employed, the self-employed rules apply.
• Freelancers and contractors: if you’re self-employed, the self-employed rules apply.
• People claiming tax relief or a refund: you may be able to get money back if you’ve paid too much tax, for example on job expenses or savings interest.

How does filing with HMRC work?

Filing with HMRC is free, but the process can be complicated.

1. Create a Government Gateway account.
2. Register for Self Assessment.
3. Request your Unique Taxpayer Reference (UTR) number.
4. Start preparing your tax return.

Expect the following when you file with HMRC:

• HMRC terminology throughout
• A hard time deciphering which sections are relevant to you
• Little help to understand the calculation of your tax bill

How does filing with Taxfix work?

Taxfix is different from filing with HMRC directly. You pay a fixed fee, and an accountant prepares your return for you to approve. You still need to register for Self Assessment and get your Unique Taxpayer Reference (UTR) from HMRC before you start.

1. Select a plan: answer a few guided questions.
2. Upload your documents: such as your P60 and your income and expense records.
3. Pay the fixed fee: from £99.
4. Review your draft: an accountant prepares your return for you to approve.
5. Approve and file: once you approve it, it is filed with HMRC.

What are the main differences between the two?

The two routes differ in several ways.

	Taxfix	HMRC
How intuitive is the platform?	Plain-English questions	Form-based, with HMRC terminology
Who prepares the return?	An accountant	You
Who reviews before filing?	You, before it is filed	You
How long does it take to file?	Depends on how quickly you upload documents and approve the draft	Depends on how quickly you prepare the return
Is there support along the way?	Your UK accountant	Online guidance and the HMRC helpline
Jargon-free?	Yes	No, HMRC terminology applies
Request UTR	Available on our Plus plan	Through HMRC registration
Cost	From £99	Free
Can you make an amendment (within a year of the Self Assessment deadline)?	Yes. Your accountant handles it.	Yes. You make the change yourself.
Getting in touch with HMRC	Our Plus and Platinum plans include support with HMRC contact	You contact HMRC yourself
Who handles HMRC queries?	You, with support on our Plus and Platinum plans	You

What happens if you make a mistake on your tax return?

If you spot a mistake, you can amend your return within 12 months of the 31 January deadline. To avoid errors in the first place, you review and approve your return before it’s filed. Check that:

• Your income and expenses match your records
• All your earnings are recorded
• Your salary income is included
• Your personal information is accurate
• Your employer details are correct
• Your profit estimates are accurate

If you file with HMRC’s online service, you prepare, submit and amend the return yourself. With Taxfix, your accountant handles any amendment.

Who pays your tax refund?

HMRC issues any tax refund and decides both the amount and when you receive it. Taxfix has no control over either.

To understand how your refund was worked out, check your tax calculation. Your Taxfix accountant can also help you clarify any points.

Which option is right for you?

Both routes can work. The right choice depends on how complex your tax affairs are and how much support you want. 

Choose HMRC online if:

• Your income comes from one source, with little else to report
• You’re comfortable with HMRC’s terms and forms
• You want to avoid fees and have time to complete the forms yourself

Choose Taxfix if:

• You’re a landlord and want an accountant to check your rental income and expenses before anything is filed
• You’re an employee with savings, dividend or capital gains income and want help making sure your return is complete
• You’re self-employed or have side income and aren’t sure what to register or report
• You’d rather pay a fixed fee than spend time on the forms

Important notes

• If you’re not sure whether you need to send a return, check the HMRC guidance on who must send a tax return.
• Taxfix is a private company and is not affiliated with HMRC.
• Your data is encrypted and submitted to HMRC through its official channel.

FAQ: Taxfix vs. HMRC

Is Taxfix an alternative to HMRC?

No. HMRC is the UK’s tax authority, and every Self Assessment return is sent to it. Taxfix is an alternative to filing directly through HMRC’s online service: it prepares your return and files it with HMRC once you approve it.

Do I still need to register with HMRC if I use Taxfix?

Yes. You still need to register for Self Assessment and get your Unique Taxpayer Reference (UTR) from HMRC. Taxfix does not replace this step. 

Is it cheaper to file with HMRC?

Yes. HMRC’s online service is free to use, while Taxfix charges a fixed fee. The price depends on the plan you choose, and whether it is worth paying depends on how much help you need.

When is the Self Assessment deadline?

For the 2025/26 tax year, the online return and payment are due by 31 January 2027. The paper return deadline is 31 October 2026.

Can I amend my return after Taxfix has filed it?

Yes. You can amend your return within 12 months of the 31 January deadline, and your accountant handles the change.