Income Tax for Self-Assessment - getting your clients MTD-ready

As As an accountant, keeping up with changes to tax regulations is a key part of the job. The government has been rolling out its Making Tax Digital (MTD) initiative over the last few years, and they frequently update key information relating to the scheme. So what do you need to know? 

From April 2026, Making Tax Digital for Income Tax (ITSA) will come into force for those who earn over £50,000. Everyone who files Self Assessment returns and meets the threshold will need to keep digital records and submit quarterly updates on their finances to HMRC.

In this article, we’ll run through some of the ITSA basics and give you some Self Assessment for accountants top tips to help you make sure your clients are ready for MTD ITSA ahead of time. We’ll also show you how our accounting software for MTD can make the whole process a bit simpler. 

What is Self Assessment Income Tax?

Self Assessment Income Tax is exactly what it sounds like. Individuals who submit Self Assessment tax returns are responsible for assessing how much tax they need to pay and paying it themselves. 

The process is simple: 

• You report how much you earned over the last tax year and subtract any expenses

• HMRC calculates how much tax you owe

• You pay HMRC by your preferred method (direct debit, bank transfer or cheque, for instance)

People with smaller or simpler businesses often submit their return and pay what they owe themselves. But those with larger or more complicated accounts tend to employ professional accountants to take care of the process for them. 

Who needs to file a Self Assessment Income Tax return?

The main set of people who need to file a Self Assessment process for income tax are self-employed sole traders, landlords and partners in business partnerships. 

All partners must complete a return, but sole traders and landlords only need to do so if their turnover was higher than £1,000 in the last tax year (6 April to 5 April). 

This might include: 

• income from savings, investments and dividends

• tips and commissions

• foreign income 

• money from renting out a property 

You can learn more about who is eligible and why on the government’s Self Assessment tax returns page.

Like a lot of the UK tax system, Self Assessment can seem a little complicated, and the rules on who needs to fill out a return aren’t always clear or easy to find. 

What are the MTD requirements for Income Tax?

MTD is a government initiative to make tax digital. This means getting rid of paper and non-digital returns entirely. 

Under the new rules, eligible businesses will need to do the following: 

• Use software for initial accounting, or transfer their accounts into electronic data. 

• Submit this electronic data to HMRC in an HMRC-approved format. 

• Make quarterly reports in addition to annual Self Assessment tax returns. 

If you have clients with a VAT-registered business and an annual turnover above £85k, you’ll already be familiar with the basics of Making Tax Digital, as MTD for VAT was made mandatory in April 2019 for this group.

When will the MTD rules apply to Income Tax?

MTD rules will apply to income tax from April 2026. That’s when the government plans to roll out MTD ITSA for businesses and landlords with an annual turnover of more than £50,000. From April 2027, it will also affect businesses and landlords with an annual turnover more than £30,000.

However, it makes sense to be well prepared for MTD so you can get your clients up to speed ahead of the deadline.

How to pay Self Assessment Income Tax online

We mentioned above that HMRC needs data to be submitted in certain formats. There’s a lot of information and advice out there on Self Assessment for accountants looking to streamline their clients’ accounts, but the best way to put your and your clients’ minds at ease is to use QuickBooks. 

With our MTD enabled software, you’ll be able to collect all relevant data to give an accurate and up-to-date view of your financial position. 

Self Assessment Income Tax deadlines

Your first quarterly return under the new system is due in the fourth month of your accounting period. You’ll then need to file another return with HMRC every three months. 

This is a significant change. At the moment, Self Assessment returns are filed annually, but under MTD, businesses will need to submit these quarterly reports as well. 

For an accounting period that matches the tax year, your reports would be due as follows: 

• 1st quarter (6 Apr to 5 Jul) is due 5 August 2026

• 2nd quarter (6 Jul to 5 Oct) is due 5 November 2026

• 3rd quarter (6 oct to 5 Jan) is due 5 February 2027

• 4th quarter (6 jan to 5 Apr) is due 5 May 2027

• 31 January 2026: End of Period statement (EPOS) and final declaration due 

HMRC still hasn’t confirmed final dates for payments, but many expect that there will also be an option to make payments throughout the year.

Note: There won’t be any late filing penalties for at least one year from April 2026, but HMRC has made clear it will charge penalties after the grace period, so it’s crucial to get on top of the new system as soon as possible.

We hope this article has helped explain both the basics of filling out a Self Assessment Income Tax return and how the new MTD scheme is set to change it. 

While your clients won’t need to start using the new system until April 2026, getting ahead of the game can make you really stand out as an accountant. 

And, even if some clients leave it too late to make the shift, you’ll have a competitive edge by not being caught up in the rush to adjust to the new scheme once April 2026 rolls around.