How to Submit Your Q1 MTD Quarterly Update: Step-by-Step

Right, Let's Just Do This

If you've been staring at your MTD software wondering where to click first, you're not alone. The Q1 deadline of 7 August 2026 is close, your records are ready, and now you just need to get the thing submitted. This guide walks you through the actual submission process - screen by screen, step by step - so you know exactly what to expect before you hit send. No jargon, no detours into record-keeping advice. Just the filing flow itself.

If your records still need work, start with our Q1 final checks pre-submission checklist first. But if you're ready to go, read on.

What You're Actually Doing When You Submit a Quarterly Update

A quarterly update is not a full tax return. It's a summary of your income and expenses for one quarter - in this case, 6 April to 5 July 2026 - sent directly to HMRC through your MTD software. HMRC uses these updates to build a running picture of your tax position across the year. You'll do four of them, then a final declaration at the end.

Nothing is paid as a result of submitting a quarterly update on its own. You're filing information, not a bill. So take a breath - this is less dramatic than it sounds.

If you're not sure how quarterly updates relate to your overall filing obligations, our post on MTD quarterly updates vs full tax return explains the difference clearly.

Before You Log In: A One-Minute Sense Check

You don't need to spend an hour preparing at this stage. But do check these three things quickly before you open the software:

• Your total income figures for Q1 are finalised and you're not expecting any late invoices or payments to add.
• Your expenses are categorised and you're happy with the totals.
• You know which income source you're filing for - self-employment, property, or both.

That's it. If those three things are in order, you're ready to file.

Step 1: Log In to AffordableMTD

Go to secure.affordablemtd.com and log in with your email address and password. If you've forgotten your password, use the reset link on the login page - it's quick.

Once you're in, you'll land on your dashboard. This is your home screen. It shows your income sources, any updates due, and the current filing status for each quarter.

Step 2: Find the Q1 Update on Your Dashboard

On the dashboard, look for the section labelled Quarterly Updates or similar. You should see Q1 (6 April - 5 July 2026) listed there with a status. If it says "Not yet submitted" or "Ready to review", that's where you're going.

Click into Q1. This opens the update for that period.

If You Have More Than One Income Source

You'll see separate Q1 updates listed - one for your self-employment business and one for your property income. You need to submit each one separately. They're independent. Completing one does not complete the other.

Start with whichever one is ready. You can submit them in any order.

Step 3: Review Your Income and Expense Totals

When you open the Q1 update, you'll see a summary screen. This shows the totals that will be sent to HMRC. These figures are pulled from the income and expense records you've already entered into the software.

You're looking at:

• Total income for the quarter - this is your gross income (the full amount received before deducting anything)
• Total allowable expenses - broken down by category
• Net profit or loss - the difference between the two

Take a moment to check these figures look right. Do the totals match what you were expecting? If something looks off, now is the time to go back and fix it - not after submission. Our post on common Q1 MTD submission errors covers the mistakes people most often catch at this stage.

Step 4: Check Any Allowances or Adjustments

Depending on your income type, there may be an adjustments section before you reach the final submit screen. This is where certain additional claims sit - things like the trading allowance or property allowance, if applicable.

If you've already set these up when you first configured your account, they should appear automatically. If you're not sure what to claim here, our post on Q1 allowances and adjustments explains what's available and how each one works.

Don't add an allowance unless you understand what it does. If in doubt, leave it out for now - you can revisit this during your final declaration later in the year.

Step 5: Confirm the Filing Period

Before submission, the software will show you a confirmation screen with the filing period clearly stated: 6 April 2026 to 5 July 2026. Make sure this matches Q1. It sounds obvious, but it's worth a second glance - especially if you've logged in to do something else recently and want to be sure you're in the right quarter.

You'll also see which income source this update covers (self-employment or property). Confirm this is correct before moving on.

Step 6: Submit to HMRC

When you're happy with everything, click the Submit to HMRC button. The software sends your data directly to HMRC's systems via an Application Programming Interface - a secure, direct digital connection. You don't need to do anything else at this point. There's no PDF to download and email, no portal to log into separately.

The submission usually takes a few seconds. Occasionally it can take a little longer if HMRC's systems are busy. Don't click submit twice - just wait.

What If It Fails?

Occasionally a submission will return an error. This can happen for a few reasons - a connection issue, an HMRC system problem, or a validation error in your figures. If this happens:

• Read the error message carefully. It will often tell you exactly what's wrong.
• If it's a data error, correct the relevant field and try again.
• If it looks like an HMRC system issue, wait a short while and try again. Our post on what to do if HMRC's MTD service is down explains your options and how deadline protection works in these situations.

Step 7: Save Your Confirmation

Once your update has been accepted by HMRC, you'll see a confirmation screen. This will typically include:

• A submission reference number
• The date and time of submission
• A summary of the figures submitted

Take a screenshot or save a copy of this confirmation. You don't need to print it, but having a record is sensible. If there's ever a question about whether you filed on time, this is your evidence.

AffordableMTD also stores your submission history inside the software, so you can come back and view it any time.

Step 8: Repeat for Any Additional Income Sources

If you have both self-employment and property income, go back to the dashboard and repeat the process for your second income source. The steps are identical - same flow, same screens, just different figures.

Both updates need to be submitted by 7 August 2026. One doesn't count for the other.

What Happens After You Submit?

HMRC receives your update and logs it against your record. You won't get a letter or an instant reply - that's normal. The update feeds into HMRC's in-year estimate of your tax position. This is used for information purposes and to keep your records current.

You don't owe anything at this point as a direct result of submitting the quarterly update. Tax payments happen separately through payments on account - our post on MTD quarterly updates vs payments on account explains how those work.

For a full picture of what comes next after Q1 is done - including what records to keep and how Q2 works - see our post on what to do after your Q1 filing.

Missed the Deadline or Think You Have?

If you've realised you've missed the 7 August deadline, don't panic and don't ignore it. File as soon as you can. Our post on what happens if you miss the 7 August MTD deadline explains the penalty system and what to do next.

There are also limited circumstances where a reasonable excuse can apply. See our guide on MTD exemptions and reasonable excuse if you think that might be relevant to your situation.

A Few Things First-Time Filers Often Worry About

"What if my figures are slightly wrong?"

Small rounding differences are not something HMRC will chase you for. If you've made a genuine error, you can amend before or after the deadline. The important thing is that you file something on time. A late submission with perfect figures is worse than an on-time submission with a minor error that you later correct.

"What if I haven't included every single expense?"

Your quarterly updates don't need to be perfect down to the penny. They're an in-year estimate. If you realise later that you missed an expense category, you can pick it up in a subsequent quarter or at your final declaration. Don't let perfection stop you filing on time.

"Is this really going to HMRC? It seems too easy."

Yes, it really is. MTD bridging software like AffordableMTD connects directly to HMRC's systems. The submission confirmation you receive is the same as a digital acknowledgement from HMRC. There's no secondary step. If you want to understand more about how bridging software works, see our plain-English explanation of MTD bridging software.

"What if I've entered income in the wrong category?"

Common mistakes like this are covered in our post on common Q1 MTD filing mistakes and how to fix them. Worth a quick read before you submit if you're unsure.

You're Ready. Here's the Short Version.

Log in. Find Q1 on your dashboard. Review your income and expense totals. Check any allowances. Confirm the filing period. Click submit. Save your confirmation. If you have a second income source, repeat. That's the entire process. Most people complete it in under ten minutes.

The Q1 deadline is 7 August 2026. With AffordableMTD, you can submit directly to HMRC without needing an accountant or any accounting background. If your records are in order, the filing itself is the easy part.