Q1 Tracking Mistakes to Avoid Before 7 August 2026

Your first Making Tax Digital quarterly update is due on 7 August 2026 - just 87 days away. If you're a sole trader or landlord with gross income over £10,000, you're probably tracking your Q1 figures right now. The problem? Most people are making critical mistakes that could cost them penalties, overpaid tax, or hours of last-minute panic.

We've seen thousands of users navigate their first MTD quarter, and the same errors crop up repeatedly. The good news is they're all preventable if you know what to look for. Here are the biggest Q1 tracking mistakes and how to fix them before it's too late.

Missing Income: The £50 Here and There Problem

The most common mistake we see is incomplete income tracking. It's not usually the big invoices people forget - it's the small stuff. The £50 cash payment. The PayPal transfer that went to your personal account. The delayed payment from March that arrived in April.

Under MTD, you must report all business income received in each quarter. HMRC's systems are getting better at spotting discrepancies between what you report and what third parties (like payment processors) tell them.

What Counts as Q1 Income?

• Any payment received between 6 April and 5 July 2026
• Cash payments (yes, even small ones)
• Bank transfers to business or personal accounts
• PayPal, Stripe, and other online payments
• Payments for work done in previous quarters but received in Q1
• Refunds or rebates received

The key word is "received". MTD uses cash basis accounting for most sole traders and landlords, so it doesn't matter when you invoiced - only when you got paid.

How to Fix It

Set up a system to capture everything:

1. Check all bank accounts weekly (business and personal)
2. Review payment platforms like PayPal every Friday
3. Keep a simple notebook for cash payments
4. Set phone reminders to record income immediately
5. Use apps that automatically import bank transactions

If you're using MTD bridging software, look for tools that connect to multiple bank accounts and payment platforms. Manual tracking always misses something.

Expense Category Chaos

The second biggest mistake is putting expenses in the wrong categories. This matters more under MTD because you're reporting quarterly, and HMRC can spot unusual patterns faster.

Common categorisation errors we see:

• Putting office supplies under "travel" because that's where they ended up in your spreadsheet
• Mixing personal and business expenses in the same category
• Using vague categories like "general expenses" for everything
• Claiming non-allowable expenses as business costs

Wrong categories don't just confuse HMRC - they can also cost you money. If you miscategorise a legitimate expense as something non-allowable, you'll pay tax on money you shouldn't.

The Most Confused Categories

Office costs vs. business premises: Rent for a dedicated office is "business premises". Desk supplies are "office costs". Don't mix them.

Travel vs. motor expenses: Fuel goes under "motor expenses". Train tickets go under "travel". Parking can go either way depending on context.

Professional fees vs. legal costs: Accountant fees are "professional fees". Solicitor fees for business matters are "legal and professional costs". They're separate categories.

For a full breakdown of what you can claim and where, check our guide to allowable expenses for MTD.

How to Fix It

Create a simple categorisation system and stick to it:

1. List the 10-15 expense categories you actually use
2. Write one-line descriptions for each ("Office costs: stationery, stamps, small equipment under £500")
3. When in doubt, pick the most specific category that fits
4. Review your categories monthly to spot mistakes early

Better yet, use software with AI-powered categorisation. It learns from your patterns and suggests categories automatically, reducing errors over time.

The Last-Minute Scramble

Here's what happens to most people: They track nothing for three months, then spend the weekend before 7 August frantically going through bank statements and trying to remember what that £147 payment to "ABC Services Ltd" was for.

This approach virtually guarantees mistakes. You'll miss transactions, miscategorise expenses, and probably claim things you shouldn't. Worse, you'll be too stressed to double-check your work.

MTD's quarterly deadlines come every three months for the next several years. If you don't build proper habits now, you'll be doing this scramble four times a year forever.

The Real Cost of Scrambling

Last-minute preparation doesn't just waste time - it costs money:

• You'll miss legitimate expenses because you can't remember what they were
• You'll make errors that trigger HMRC queries later
• You might miss the deadline entirely and face penalties
• The stress will probably put you off doing business admin for months

MTD penalties start at £200 for missing your first deadline. They go up from there.

How to Fix It

Build a simple monthly routine instead:

1. Week 1: Download bank statements and check for new transactions
2. Week 2: Categorise any unclear expenses while you still remember
3. Week 3: Chase any outstanding invoices
4. Week 4: Review your numbers and spot-check for obvious errors

Spend 30 minutes a week instead of six hours in panic mode. Your future self will thank you.

Poor Record Keeping

Even people who track income and expenses often keep terrible records. Shoebox full of receipts, bank statements in random folders, important documents saved as "Document1.pdf" on the desktop.

This creates problems beyond just finding things. HMRC can request records going back several years. If you can't produce clean, organised documentation, you could face penalties even if your original filing was correct.

What Records You Need

For each transaction, keep:

• The receipt or invoice
• Evidence of payment (bank statement line, card receipt)
• A note explaining what it was for (if not obvious)
• The date and amount

For digital records, make sure filenames include dates and descriptions. "2026-04-15-office-supplies-staples.pdf" is much better than "receipt.pdf".

How to Fix It

Create a simple filing system:

1. One folder per tax year
2. Sub-folders for receipts, bank statements, invoices
3. Consistent naming: date, description, amount
4. Backup everything in two places (cloud and local)
5. Review and organise monthly, not quarterly

Digital tools help enormously here. Good MTD software stores your records automatically and makes them searchable. No more hunting through folders for that one receipt.

Not Understanding Mixed Income Rules

Many people have income from multiple sources - employment, self-employment, rental property. The rules about what you need to report quarterly can be confusing.

The key point: MTD only applies to self-employment and property income. If you're employed and also do freelance work, you only report the freelance income quarterly. Your employment income still goes on your annual tax return as normal.

But here's where it gets tricky - you need to track which expenses relate to which income stream. You can't claim employment expenses against self-employment income, and vice versa.

Common Mixed Income Scenarios

Employed + freelancer: Report freelance income quarterly, employment income annually. Keep expenses separate.

Multiple rental properties: All rental income goes in your quarterly property update, even if the properties are in different locations or property types.

Self-employed + rental: These need separate quarterly updates. Don't mix self-employment and property income in the same submission.

For detailed guidance on mixed income situations, see our post on choosing MTD software by income type.

Ignoring the Digital Requirement

Some people are still trying to manage MTD with paper records and basic spreadsheets. This creates unnecessary work and increases error rates.

MTD requires you to keep digital records and submit updates through compatible software. You can't just fill in a form on the HMRC website like you used to.

The good news is that "digital records" doesn't mean complex systems. A simple cloud-based spreadsheet counts. Many MTD tools are specifically designed for small businesses and cost less than £10 per month.

What Counts as Digital Records

• Cloud-based spreadsheets (Google Sheets, Excel Online)
• Dedicated bookkeeping software
• MTD bridging software
• Apps that sync with your bank account

What doesn't count:

• Paper records only
• Spreadsheets stored only on your computer (not backed up)
• Notes in your phone that aren't part of a proper system

For most sole traders and landlords, you don't need expensive accounting software. MTD bridging software handles the quarterly reporting requirement without the complexity of full bookkeeping systems.

Getting Back on Track Before 7 August

If you recognise yourself in any of these mistakes, don't panic. With 87 days until the deadline, there's still time to fix things.

Start with the biggest risks first:

1. Check for missing income: Go through all bank accounts and payment platforms since 6 April
2. Review expense categories: Make sure everything is in sensible categories and nothing personal has crept in
3. Organise your records: Get receipts and bank statements in order now, while transactions are still recent
4. Set up proper systems: Don't just fix the current quarter - build habits that will work for Q2 and beyond

Remember, this is just your first quarterly update. You'll be doing this every three months, so it's worth investing time now to get the system right. The habits you build before 7 August will save you hours over the coming years.

For more guidance on preparing for MTD, check our complete MTD checklist and our guide to MTD start dates and deadlines.