If you’re a self-employed dentist with income over £50,000, Making Tax Digital for Income Tax has applied to you since 6 April 2026. Most of the talk so far has been about quarterly updates and software. Much less has been said about something that will matter in January: where your tax bill now shows up, and how you pay it.

At the same time, HMRC has been building up its mobile app into one of the main ways people deal with their tax. The two changes overlap more than you’d expect, so we’ve covered both here.

What the HMRC app can do now

The HMRC app has been around for ten years, but it’s only fairly recently that it has become properly useful for self-employed people. HMRC says 7.6 million people used it in 2025/26, and 2.8 million of those were new users.
For self assessment, you can now use it to:

• see how much you owe and pay your bill directly
• set payment reminders and add self assessment deadlines to your phone’s calendar
• find your UTR without hunting for an old letter
• track letters HMRC has sent you and read messages from them
  check your employment and income history for the last five years, which is handy if you’ve had PAYE work alongside associate income or a mortgage broker is asking for it
• tell HMRC you no longer need to send a tax return

Paying through the app has taken off. HMRC reported a rise of nearly 65% in self assessment payments made that way, with around 340,000 people paying their bill through it.

HMRC has also been looking at adding a service to the app that would let you pay towards your tax bill in instalments during the year. Nothing has launched yet, but if you dread one large payment in January, it’s one to watch.

One word of caution. The app is good for checking and paying. It only shows what HMRC holds, and under MTD that information is now split across two places.

MTD and payments on account: what has moved

The payment dates haven’t changed. You still pay on 31 January and 31 July, and each payment on account is still normally half of the previous year’s bill. What has changed is where those amounts are recorded.

Once you’re in MTD, HMRC moves your payments on account into a new Making Tax Digital account, separate from the self assessment online account you’ve been using for years. Older amounts, such as an unpaid balancing payment from before you joined, stay in the old account.

HMRC has written to people who joined MTD voluntarily for 2025/26 to explain this. Their 2025/26 payments on account now sit in the MTD account, and on statements from the old account they appear as ‘transferred to digital’. We have also experienced cases where people who only joined in April 2026 have had their 2025/26 payments on account moved across too.

HMRC’s own advice is to check both accounts and pay whatever is shown as due in each.

Two other things now happen in the MTD account rather than the old one. If your income has dropped and you want to reduce your payments on account, that’s done in the MTD account. And if the MTD account shows you’ve overpaid, you reclaim it through HMRC’s new online service for MTD.

Why this matters for January 2027

For most associates who came into MTD in April 2026, January 2027 is the first payment date where this really bites. On 31 January you’ll usually owe the balancing payment for 2025/26 plus your first payment on account for 2026/27.

Those two amounts may well be in different accounts. If you log in to one, pay what you see and assume that’s it, part of the bill could go unpaid without you knowing. Interest runs on anything paid late, including payments on account, from the due date.

It’s also worth taking care with payment references. A payment that lands against the wrong year or the wrong account can take time to untangle, and in the meantime HMRC’s records can show you as owing money you’ve already paid.

What we’d suggest

• Get the app set up now. Sign-in problems are common, and 30 January is a bad time to discover yours.
• Don’t rely on one figure. Until HMRC finishes moving everything across, the number in one account may not be your full bill.
• Let us check it for you. As part of preparing your January figures, we’ll look at both accounts and tell you how much to pay and where it needs to go.
• Get your return information to us. We can only confirm the 2025/26 balancing payment once your return is done, and the earlier we have your information, the more time you have to plan for it.

If you’re not sure whether MTD applies to you yet, or you’ve had a letter from HMRC about payments on account and aren’t sure what it means, get in touch and we’ll go through it with you.