Sole Trader Q1 MTD Filing Checklist: What to Gather in 14 Days

Your Q1 MTD Filing Checklist: What to Gather in the Next 14 Days

The 7 August deadline for your first MTD quarterly update is close. If you have not yet gathered your records, you still have time - but not much. This checklist is written for sole traders with self-employment income only. It tells you exactly what to collect, how to check it, and what to verify before you file. Work through it in order and you will not miss anything important.

What Is a Quarterly Update, and What Does It Cover?

A quarterly update is a summary of your self-employment income and expenses for a specific three-month period. Q1 covers 6 April to 5 July 2026. You are not paying tax at this stage - you are just reporting figures to HMRC through your MTD software. The tax calculation comes later, at your end-of-year final declaration.

If you are unsure what the update actually contains, the post What to Include in Your MTD Quarterly Update: The Bare Essentials explains each section clearly.

Step 1 - Gather Your Income Records (Days 1 to 3)

Start here. Before you touch expenses, make sure your income figure is correct.

What counts as self-employment income?

Include every payment you received for goods or services during the Q1 period - 6 April to 5 July 2026. That includes:

• Invoices paid during the period (even if the invoice was raised earlier)
• Cash payments received
• Bank transfers from clients or customers
• Payments received through platforms such as PayPal, Stripe, or similar
• Any payments in kind (goods or services given to you instead of money)

MTD uses cash basis accounting by default for sole traders. That means you record income when you actually receive it - not when you invoice. So if a client paid you in May for work you did in March, that payment belongs in Q1.

How to check your income figure

1. Open your bank statements for April, May, and June (and up to 5 July).
2. List every payment in from clients or customers.
3. Add payments received through any payment platforms separately, then combine.
4. Cross-reference against your invoices or sales records.
5. Confirm the total matches what you have recorded in your software or spreadsheet.

Common errors at this stage include missing a payment that came in via a different account, double-counting a payment that appeared in two places, and forgetting platform fees that were deducted before the money reached your bank. The post Sole Trader Q1 MTD Income Mistakes: How to Avoid Them covers these in more detail.

Step 2 - Gather Your Expense Records (Days 3 to 7)

Expenses reduce your profit and therefore reduce how much tax you will eventually pay. Getting them right matters. Spend more time here than on any other step.

The main expense categories for sole traders

HMRC uses specific categories for self-employment expenses. Make sure you are recording costs under the correct heading, not just lumping everything together. The main categories are:

• Goods bought for resale or used in your work - stock, materials, and direct costs of producing what you sell
• Staff costs - wages or subcontractor payments if you use other people
• Premises costs - rent for a workshop, studio, or business premises (not your home)
• Repairs and maintenance - fixing business equipment or premises
• Phone and internet - the business proportion of your bills
• Vehicle and travel costs - fuel, parking, train fares, or mileage claims
• Office costs - stationery, postage, printer ink, and similar
• Advertising and marketing - website costs, ads, business cards
• Professional fees - accountant fees, software subscriptions, legal costs
• Financial charges - bank charges, interest on business loans
• Use of home as office - if you work from home, a proportion of household costs

For a full breakdown of what qualifies under each heading, see Allowable Expenses for MTD: What You Can Claim as a Sole Trader or Landlord.

Expenses that are only partly business use

If you use something for both personal and business purposes - a mobile phone, a car, a home broadband connection - you can only claim the business proportion. You need to work out a reasonable percentage and stick to it. For example, if you use your phone 60% for business, you claim 60% of the cost.

The post Mixed-Use Expenses and MTD: Claiming the Business Percentage walks through how to calculate and justify that split.

Vehicle costs and mileage

Most sole traders find it simpler to claim a flat mileage rate rather than actual vehicle costs. The HMRC rate for cars is 45p per mile for the first 10,000 miles in the tax year. Keep a log of every business journey - date, destination, reason, and miles. If you have not kept a log, reconstruct it now from your diary, calendar, or client records while you still can. The post Mileage Allowances for MTD: Claiming Simplified Rates in Q1 explains this in detail.

Collecting your receipts and invoices

1. Go through your bank statements line by line for April, May, and June.
2. For each business payment out, find the receipt or invoice.
3. Assign each cost to a category.
4. Note where you need to apply a business percentage split.
5. Collect digital copies - photos, PDFs, or scans - and store them somewhere you can find them later.

If you have a large number of expenses to enter, the CSV import tool in AffordableMTD can save significant time. See Importing Q1 Expenses: CSV Format and AI Categorisation for a guide to using it.

Step 3 - Check Whether the Trading Allowance Applies (Day 7)

The trading allowance is £1,000 per tax year. If your total self-employment gross income for the year is £1,000 or less, you do not need to report anything. If your income is over £1,000 but your actual expenses are less than £1,000, you might benefit from claiming the flat allowance instead of itemising your costs.

You cannot claim both the trading allowance and your actual expenses - it is one or the other. If your Q1 income was low, check whether this applies to you before going any further. The post Trading Allowance for Sole Traders: MTD Q1 Explained covers the rules and when it makes sense to use it.

Step 4 - Run Your Pre-Submission Verification (Days 8 to 11)

Before you file anything, work through this verification list. These are the checks that catch errors before they become problems.

Income verification

• Does your total income match your bank statement deposits from clients and customers?
• Have you included all payment methods - bank transfers, cash, online platforms?
• Have you excluded any non-business payments (personal transfers, refunds, loan repayments)?
• Are all figures in the correct period (received between 6 April and 5 July 2026)?

Expenses verification

• Does every expense have a receipt or invoice you can produce if asked?
• Have you applied the correct business percentage to any mixed-use costs?
• Are expenses assigned to the correct HMRC category?
• Have you excluded any personal spending that has accidentally crept in?
• If you are claiming mileage, does your log support the total number of miles?
• Have you excluded any capital purchases (equipment, vehicles) - these are handled separately as capital allowances, not as regular expenses?

Software or spreadsheet check

• Does the total in your software match the total you calculated manually?
• Are there any unexplained rounding differences?
• Have you categorised everything, or are there items sitting in an "uncategorised" bucket?

Step 5 - Check You Are Filing Under the Right Business (Days 11 to 12)

If you have more than one self-employment business - for example, you do freelance design work and also run a separate market stall - each business is reported separately in MTD. Make sure you have not mixed income or expenses from different businesses into the same set of records.

The post Multiple Self-Employment Businesses and MTD: Threshold Rules Explained covers how multiple businesses are treated for registration and reporting.

Step 6 - Check Your Allowances and Adjustments (Day 12)

At the quarterly update stage, you are primarily reporting income and allowable revenue expenses. Some adjustments - such as capital allowances, personal allowances, and certain reliefs - are handled at the end-of-year final declaration rather than in the quarterly update itself.

However, it is worth noting what you will need later so you are not scrambling at year end. Keep records now of:

• Any equipment purchased during Q1 that may qualify for the Annual Investment Allowance
• Any overlap relief you might be carrying forward
• Pension contributions made during the period

For more on what can be claimed in the quarterly update versus what waits until the final declaration, see Q1 Allowances and Adjustments: What to Claim in August 2026.

Step 7 - Final File Preparation and Submission (Days 13 to 14)

You are nearly there. Before you submit:

1. Log into your MTD software and review the figures on screen against your own records one final time.
2. Make sure the period shown (6 April to 5 July 2026) is correct.
3. Confirm the income and each expense category total matches what you have calculated.
4. Check there are no red flags or warnings from the software.
5. Submit before 7 August - not on the morning of 7 August if you can help it, in case of any last-minute technical issues.

The step-by-step process for submitting through AffordableMTD is covered in How to Submit Your Q1 MTD Quarterly Update: Step-by-Step.

If you are worried about what happens if something goes wrong on the day, see MTD Service Down? What to Do If HMRC Issues Affect Your Deadline.

What to Keep After You File

Filing is not the end of it. HMRC can ask you to produce supporting records. Keep all receipts, invoices, bank statements, mileage logs, and any other documents that back up what you filed. HMRC's rules require you to keep records for at least five years after the 31 January filing deadline for the relevant tax year. The post After Your Q1 MTD Submission: What Records You Must Keep explains exactly what to keep and for how long.

If You Miss the Deadline

Missing the 7 August deadline can result in penalty points under HMRC's new points-based system. A single missed deadline will not immediately result in a financial penalty, but points accumulate. Do not assume a short delay is harmless. The post What Happens If You Miss the 7 August MTD Deadline explains how the penalty system works.

Quick-Reference Checklist

Print this out or save it somewhere useful:

• Bank statements pulled for 6 April to 5 July 2026
• All client or customer payments listed and totalled
• Platform payments reconciled (PayPal, Stripe, etc.)
• All business expenses listed with receipts
• Mixed-use expenses split by business percentage
• Mileage log completed and total calculated
• Expenses categorised correctly under HMRC headings
• Trading allowance checked (if income is low)
• Figures entered into MTD software and reviewed
• Software totals cross-checked against manual calculation
• Submitted before 7 August 2026
• Confirmation of submission saved
• Records stored for future HMRC enquiries

Putting It Together

Fourteen days is enough time to get this right if you work through the steps above in order. Start with income, move to expenses, verify everything, and submit with a few days to spare. The most common errors - missing income sources, claiming personal costs, and forgetting to apply percentage splits - are all avoidable with the checks above. Once Q1 is filed, you can turn your attention to Q2, which starts on 6 July and follows the same process.