Before you submit your digital records for MTD, run through this: records up to date, bank reconciled, nothing duplicated, income sources all included, and the right period selected in your software. That’s it, that’s the checklist.
One thing worth clarifying first: sending a quarterly update isn’t the same as paying tax. You’re reporting running totals to HMRC, not settling a bill, so nothing’s due right now. Your actual tax is worked out and paid through your Self Assessment return, as usual. A quarterly update is a health check, not an invoice.
So, let’s get into the detail.
Confirm the period and deadline
Know which quarter you’re submitting and when it’s due. On standard tax-year periods, deadlines fall on 7 August, 7 November, 7 February and 7 May. There’s no penalty for missing one in 2026/27, but treat the deadline as real anyway.
Here’s the part that catches people out: each update isn’t a three-month slice standing alone. It’s a cumulative, year-to-date figure running from 6 April, so your November update covers April to October in full. Forget that and you’ll either double-count income or submit a figure that doesn’t match what HMRC expects.
If you’re on calendar quarter periods instead of standard ones, check that your software is actually set to that, not defaulting back to standard. With more than one income source, a sole trade and a rental property, say, confirm each has its own update for the period. Open your software now and check it matches what you expect.
Check that all income and costs are there
This is where most pre-submission time should go. Start by reconciling your bank feed against your software records. Is everything that landed in your business account actually showing up, and does nothing sit there unexplained or uncategorised?
Next, check your invoices. Have you raised one for every job or sale in the period, and does every invoice issued actually appear in your records, not just the ones you remembered to log? If you take cash payments, this is the one that’s easy to miss entirely, since it never touches a bank feed. Go through manually and check that cash income has been entered.
Don’t forget payment processors either. If you take card payments, PayPal, Stripe, or similar, the amount that hits your bank is usually net of fees. Make sure you’re recording the gross sale and the fee as a separate expense, rather than just the net figure that landed, or your income will be understated.
On the expenses side, check that nothing’s sitting in a receipts folder unlogged. Have you included everything, from the obvious running costs to the smaller ones that get forgotten, like subscriptions or mileage?
Finally, think about whether you have more income sources than you’re actively tracking. A second rental property, a small side trade, or occasional freelance income can all fall under your MTD obligations and need their own place in your records, not just a mental note to deal with later.
Spot common errors before submitting
A few mistakes show up again and again, so it’s worth scanning for them specifically rather than just trusting the total looks about right.
- Duplicates are the big one, especially around invoices that get entered once manually and again when a payment processor syncs automatically. Check for the same transaction appearing twice before you submit.
- Missing records are the opposite problem: a gap in a bank statement, a week where nothing was logged, or a source that simply didn’t get set up in your software yet. If a period looks suspiciously quiet, that’s usually why.
- Personal transfers are another common trip-up. Moving money between your own accounts, or paying yourself, isn’t business income or an expense, and it shouldn’t appear in your figures at all. If it’s sitting in there, it’ll inflate your reported turnover or costs.
- Category coding matters more than it seems. The wrong heading won’t change your bottom line, but it distorts what HMRC sees your business doing, so it’s worth a quick scan rather than leaving everything lumped together.
- Refunds need handling correctly too, as a credit against the original transaction rather than a new, separate expense or income line.
One reassurance: you don’t need to make year-end tax adjustments, like capital allowances or complex accounting treatments, before a quarterly update. Those belong at your final declaration, not here. A quarterly update just needs accurate, complete income and expense figures for the period, nothing more sophisticated than that.
Send the update and check confirmation
Once you’re confident the figures are right, submit through your MTD-compatible software, not directly through HMRC’s website, since quarterly updates have to go through recognised software. If you haven’t already, it’s worth double-checking your software is properly authorised to connect to your HMRC account before you rely on it at crunch time.
After you submit, don’t just assume it’s gone through. Your software should show a clear confirmation that the update was received, and it’s worth logging into your HMRC online account afterwards to check the submission appears there too. The two should match up.
It’s also sensible to keep your own record of what you sent and when. A screenshot of the confirmation screen, or an exported copy of the figures submitted, takes seconds and could save you a headache if there’s ever a query later or a mismatch between what you think you sent and what HMRC has on file. You don’t need anything elaborate, just enough that you could reconstruct what happened if asked.
If a submission fails or hangs, don’t keep retrying blindly. Check your software’s status page first, since repeated failed attempts can create their own confusion in your records.
What to do if you discover an error later
Spot a mistake after you’ve already submitted? Don’t panic, and don’t wait for the next deadline to deal with it. Correct your digital records as soon as you notice the error.
Because updates are cumulative, this is forgiving. You don’t need a special amendment for most errors; your next update carries the correct year-to-date figures forward, and the corrected total replaces what was there before. One wrong entry in Q1 gets absorbed the moment Q2 reflects accurate records.
The exception is if you’ve already submitted your final declaration for the year. At that point, the cumulative route has closed, and you’ll need to amend your Self Assessment return directly instead.
On penalties, there’s some breathing room right now. HMRC has confirmed no penalty points apply for late quarterly updates during the current tax year. That’s not a reason to let errors sit. Fix what you find, keep your records current, and check your software for your next deadline so it doesn’t creep up on you.
For more information on MTD, check out our complete guide.
