Q1 MTD Record Fixes: 29 Days to Clean Up Before 7 August

29 Days Left - Here's How to Fix Your Q1 Records Before It's Too Late

If you know your Q1 records have problems but you haven't done anything about them yet, you're not alone - and you still have time. With 29 days until the 7 August deadline, this is the point where most sole traders and landlords either sort things out or end up filing messy, inaccurate numbers they'll regret. This post covers the three most common record problems showing up at this stage, and exactly what to do about each one before the clock runs out.

Why the Final Four Weeks Are the Riskiest

The last month before any deadline is when errors tend to pile up. You've spent weeks adding income and expenses, and now the total doesn't look right. Or you've found a receipt from April that wasn't logged. Or you've just noticed the same invoice appears twice.

These aren't unusual problems. They're normal. The difference between a clean Q1 update and a problematic one usually comes down to whether you act on them now or leave them.

The good news is that none of these issues are particularly hard to fix. You just need to know where to look and what to do.

Problem 1: Missing Receipts and Unrecorded Expenses

This is the most common issue at this stage. You know you spent money on something business-related in April, May, or June - but you can't find the receipt, or it was never logged.

What counts as a missing receipt problem

• Cash purchases with no receipt kept
• Small card payments you forgot to log
• Expenses paid from a personal account that weren't transferred to your records
• Invoices from suppliers that went into email and were never imported
• Mileage that wasn't recorded at the time

How to fix it

Start with your bank statements for April, May, and June. Go through every transaction line by line and cross-reference with what's in your Q1 records. Any payment to a supplier, subscription, or business expense that isn't already logged needs to be added.

If you have a business bank account, this is straightforward. If you use a personal account for business payments, it takes more care - but it's still doable in a few hours.

For cash purchases where you no longer have the receipt, HMRC does accept that some small expenses won't have paper records. But the expense still needs to be credible, correctly categorised, and not inflated. Don't guess at amounts you genuinely can't recall.

For mileage, if you kept even rough notes - in a calendar, in your phone, anywhere - use those to reconstruct your mileage log. Our post on mileage allowances and simplified rates for MTD explains how to calculate what you can claim.

Using the AI import tool to catch gaps

If you have a CSV export from your bank, you can upload it directly to AffordableMTD. The AI categorisation tool will scan each transaction and suggest the most likely expense category. This is particularly useful for finding payments you'd forgotten about entirely - they're sitting in your bank export, they just never made it into your records.

More detail on how the import works is in our post on importing Q1 expenses by CSV with AI categorisation.

Problem 2: Duplicate Expenses

Duplicates creep in more easily than you'd expect. You add something manually, then later import a bank statement that includes the same transaction. Or you log an invoice when you receive it, then log the same payment again when it clears.

Duplicates inflate your expense total and reduce your reported profit below what it actually was. That's not a small rounding issue - it's a factual error in your update, and it's the kind of thing that can flag a discrepancy when HMRC cross-checks data sources.

How to spot duplicates

• Sort your expenses by amount and look for identical figures appearing twice
• Check for the same supplier name appearing on the same or adjacent dates
• Look for expenses that appear in both your manual records and an imported CSV
• Check recurring expenses (monthly subscriptions, rent on a business premises) - these should appear exactly once per month

How to fix duplicates

Delete the duplicate entry, not both. Make sure you're keeping the one with the correct date and category. If the two entries have slightly different details, keep the more accurate one.

After removing duplicates, your expense total should drop. If it drops significantly, that's worth noting - your Q1 profit figure will increase, which may affect any provisional tax estimate you've been working from.

Our post on fixing messy expense records before August goes into more depth on cleaning up bulk record problems if your situation is more complex.

Problem 3: Miscategorised Items

Putting an expense in the wrong category doesn't change your total expenses or your profit figure - but it does affect the accuracy of your return and can cause problems during an enquiry. HMRC expects expenses to be in the right place.

The most common miscategorisation errors at this stage:

• Office costs logged under professional fees, or vice versa
• Travel and subsistence mixed in with motor expenses
• Equipment purchases (which may need to be capital allowances, not expenses) logged as general costs
• Subscriptions to professional bodies logged as general admin rather than professional membership
• Repairs to a rental property logged under the wrong property or wrong category

How to fix miscategorised items

In AffordableMTD, you can edit the category on any expense entry directly. You don't need to delete and re-add - just open the entry and change the category to the correct one.

If you're not sure which category something belongs in, our post on allowable expenses for MTD covers the main categories for both sole traders and landlords with examples of what goes where.

One area that catches people out: if you've bought equipment worth more than a few hundred pounds, it may not belong in your expenses at all. Capital items - things you'll use over several years - are typically handled through capital allowances, not as a direct expense. If you've logged a laptop, a vehicle, or significant tools as a straight expense, check whether they should be reclassified. This is worth looking at now rather than after you've submitted.

For landlords: property expense categories matter more

If you're a landlord, the distinction between allowable revenue expenses (repairs, letting agent fees, insurance) and capital improvements (extensions, conversions) is particularly important. Improvements are not deductible as an expense against rental income in the same way - they're handled differently. Getting this right now means you're not creating a problem for your final tax return later in the year.

See our post on what landlords must include in their Q1 filing for a full breakdown of property income categories.

What to Do If You Have All Three Problems

If you've got missing receipts, duplicates, and miscategorised items all at once, it can feel overwhelming. It isn't. You just need to work through them in the right order.

1. Remove duplicates first. Get your expense list down to one accurate entry per transaction. Don't try to categorise anything until you know each item appears only once.
2. Add missing expenses. Go through your bank statements and add anything that should be there. Use the CSV import if you have a full export - it's faster than adding entries manually.
3. Check categories last. Once your list is complete and clean, go through and correct any categories that are wrong. This is easier when you're not simultaneously adding or removing items.

If you haven't already run through our Q1 final reconciliation checklist, now is the right time. It covers income as well as expenses - because missing income entries are just as much of a problem as missing expense records.

How Long Will This Actually Take?

Realistically:

• Checking for duplicates: 30 to 60 minutes for most people
• Importing a bank CSV and reviewing AI suggestions: 45 minutes to 2 hours depending on transaction volume
• Reviewing and correcting categories: 30 to 90 minutes

Most people can get through all three in a single working afternoon. The psychological barrier - deciding to sit down and do it - is usually bigger than the actual task.

With 29 days left, you have more than enough time. But the longer you wait, the less time you'll have to deal with anything unexpected that comes up during the process.

After You've Fixed Your Records

Once you've cleaned everything up, review your totals. Check that your income figure matches what you actually received in Q1. Check that your expenses look reasonable and add up correctly. If something looks off, investigate it before you submit rather than after.

If you spot something after you've already submitted your Q1 update, it's not the end of the world. You can amend a submitted quarterly update. Our guide on how to correct a submitted Q1 MTD update explains how that works and what the time limits are.

You'll also want to think about Q2, which has already started (from 6 July 2026). Starting Q2 with clean habits now prevents the same problems coming back in three months. Our post on managing Q1 final edits while starting Q2 covers how to handle both at once without losing track of either.

The Short Version

With 29 days to go, you have enough time to fix Q1 record problems - but only if you start this week. Remove duplicates, add missing expenses using your bank statements and the CSV import tool, and correct any categories that are wrong. Work through these in order and you'll have clean, accurate records ready to submit well before 7 August. The fixes are not complicated. The only thing standing between you and a clean Q1 update is sitting down and doing it.