Import Your Expenses Fast: CSV Upload and AI Categorisation Guide

Why Bulk Import Beats Manual Entry When You're Short on Time

If you have 24 days until the 7 August deadline and a folder full of bank statements, receipts, and spreadsheet rows you haven't touched since April, manually typing expenses one by one is not going to work. AffordableMTD's CSV import lets you pull in hundreds of transactions at once, and the built-in AI categorisation does the heavy lifting of sorting them into the right HMRC fields. This guide walks you through exactly how to do it - from preparing your file to reviewing the results before you submit your quarterly update.

What You Need Before You Start

You do not need any special software to create a CSV file. A CSV (comma-separated values) file is just a spreadsheet saved in a particular format. Microsoft Excel, Google Sheets, and LibreOffice Calc can all save files as CSV. Your bank may also let you export your transactions directly as a CSV.

Before you open AffordableMTD, gather the following:

• Your bank or card statements for the Q1 period (6 April 2026 to 5 July 2026)
• Any receipts or invoices you have stored separately
• A note of any expenses you paid in cash, so you can add those manually afterwards

If your records are genuinely messy right now, it is worth reading Fixing Messy Expense Records Before August: A Q1 Reality Check first. That post helps you work out which transactions actually count before you start importing anything.

Step 1 - Export Your Transactions From Your Bank

Most UK banks offer a CSV export from their online banking or mobile app. Look for a button labelled "Export", "Download", or "Statement" in your transaction history. Select the date range from 6 April 2026 to 5 July 2026 and choose CSV as the file format.

Every bank formats its CSV slightly differently. Some put the date in the first column, some put a description, some include a balance column you do not need. That is fine - you will tidy it up in the next step.

Step 2 - Format Your CSV to Match AffordableMTD's Template

AffordableMTD expects your CSV to have columns in a specific order. The required columns are:

1. Date - in DD/MM/YYYY format (for example, 14/05/2026)
2. Description - a short note about what the transaction was (for example, "Shell Garage - fuel" or "Amazon - printer paper")
3. Amount - the expense amount as a positive number, without a currency symbol (for example, 45.80)

You do not need to add a category column yourself. The AI categorisation handles that after import.

Open your bank export in a spreadsheet programme. Delete any columns you do not need - things like running balance, sort code, or account number. Rename the columns so the headings match exactly: Date, Description, Amount. Then check that your dates are all in DD/MM/YYYY format. Some banks export dates as YYYY-MM-DD or with full month names - change these before you save.

Once your three columns are correct, go to File - Save As - and choose CSV (Comma Delimited) or CSV UTF-8 as the file type. Give the file a clear name such as "Q1-expenses-april-july-2026.csv" so you can find it easily.

Step 3 - Upload the File in AffordableMTD

Log in to your AffordableMTD account. From your dashboard, go to the Expenses section and select "Import Expenses". You will see an option to upload a CSV file.

Click "Choose File", select the CSV you prepared, and click "Upload". The system will check your file format before processing it. If there is a problem - a missing column heading, a date in the wrong format, or an amount that includes a pound sign - you will see an error message explaining what to fix.

Common upload errors and how to fix them:

• "Column heading not recognised" - Check that your column headings are exactly Date, Description, Amount with capital first letters and no extra spaces.
• "Invalid date format" - Make sure all dates are DD/MM/YYYY. If your spreadsheet has reformatted them, select the column, format cells as text, and re-enter a few dates to check.
• "Amount contains non-numeric character" - Remove any pound signs (£), commas in numbers (write 1450.00 not 1,450.00), or minus signs. Amounts should be plain positive numbers.

Once the file uploads without errors, you will see a preview of your transactions on screen before they are processed.

Step 4 - Let the AI Categorisation Run

After a successful upload, AffordableMTD's AI categorisation reads the description of each transaction and suggests which HMRC expense category it belongs to. It uses the wording from your bank descriptions, common merchant names, and spending patterns to make these suggestions.

HMRC expense categories for sole traders include things like:

• Office costs (stationery, printer ink, software subscriptions)
• Travel costs (fuel, train tickets, parking)
• Clothing (uniforms or protective wear only - not regular clothes)
• Staff costs (wages or subcontractor payments)
• Resale goods (stock you bought to sell on)
• Legal and financial costs (accountant fees, bank charges)
• Marketing and advertising (website hosting, ads)
• Training (courses directly related to your work)

Landlords have a different set of categories - things like property repairs, letting agent fees, insurance, and mortgage interest. If you are both a landlord and a sole trader, make sure you are importing expenses into the correct business type within your account. There is more detail on landlord-specific categories in What Counts as a Landlord Expense in Your Q1 MTD Quarterly Update.

The AI categorisation works best when your bank descriptions are clear. "SHELL GARAGE LONDON" will be correctly identified as fuel. "JOHN SMITH REF 48291" probably will not - the system will flag it as needing your review.

Step 5 - Review and Correct the Suggested Categories

Do not skip this step. The AI categorisation gets most transactions right, but it is not perfect and HMRC holds you responsible for the accuracy of your submissions - not the software.

After processing, you will see a list of all imported transactions with the suggested category shown next to each one. Transactions the system is unsure about are flagged for your attention.

Work through the flagged items first. For each one:

1. Read the description and recall what the payment was for.
2. Select the correct category from the dropdown list.
3. If the expense is partly business and partly personal (for example, a phone bill you use for both), enter only the business portion of the amount before confirming.

Then scroll through the auto-categorised items and spot-check them. Pay particular attention to:

• Supermarket transactions (the system may assume these are business supplies when some could be personal)
• Amazon or general online retailer purchases (often correct, but worth checking)
• Fuel (should be under Travel, not Office costs)
• Any large one-off payments that could be capital items rather than expenses

A capital item is something with a lasting value - a laptop, a van, equipment. These are not straightforward expense deductions and are handled differently for tax purposes. If you are unsure whether something is a capital item or a regular expense, check with HMRC's guidance or speak to an accountant before including it.

Step 6 - Add Any Missing Expenses Manually

Your CSV will only contain transactions that went through your bank or card. Cash expenses, mileage, and use-of-home costs need to be added separately.

In AffordableMTD, after your import is complete, use the "Add Expense" button to enter these one at a time. For mileage, use HMRC's approved mileage rate of 45p per mile for the first 10,000 miles in the tax year (25p thereafter). You cannot claim actual fuel costs if you are claiming mileage - it is one or the other. The guide to Mileage Allowances for MTD: Claiming Simplified Rates in Q1 explains how to calculate and record this correctly.

Use-of-home expenses - claiming a portion of your home costs if you work from home - are also not in your bank feed in a straightforward way. HMRC has a simplified flat-rate allowance you can use instead of calculating the exact proportion of your household bills. Check Allowable Expenses for MTD: What You Can Claim as a Sole Trader or Landlord for the current flat rates.

Step 7 - Confirm and Save Your Imported Expenses

Once you are happy with the categories and have added any missing items, confirm the import. Your expenses will now appear in your Q1 records alongside any income you have already entered.

Before you move on to submitting your quarterly update, do a basic sense-check:

• Does the total expense figure look roughly right compared to what you spent between April and July?
• Are there any obvious duplicates - transactions that appear twice because you exported from two different sources?
• Do your income and expense figures both cover the same period (6 April to 5 July 2026)?

If you want a more thorough checklist before submission, Q1 Final Checks Before 7 August: Pre-Submission Checklist covers each pre-submission step in order.

What Happens If You Have Multiple Income Sources

If you are both a sole trader and a landlord, you will need to run separate imports for each. Sole trader expenses and property expenses sit in different parts of your MTD record and map to different HMRC fields. Do not mix them into one CSV upload. Log in, select the relevant business, and complete the import process separately for each.

There is a detailed guide on managing both income types together at Multiple Income Sources and MTD: Self-Employed and Landlord Together.

How to Handle Expenses You Are Not Sure About

If you are genuinely unsure whether something is allowable - whether you can claim it as a business expense - the safest approach is to leave it out rather than include it and hope for the best. HMRC can and does check quarterly update figures, and including something that does not qualify as a business expense is worse than missing a deduction you were entitled to.

For a detailed breakdown of what counts and what does not, see Allowable Expenses for MTD: What You Can Claim as a Sole Trader or Landlord.

If you have already submitted your Q1 update and then realise you included something wrong, you can correct it. The amendment process is explained in Amending Your Q1 MTD Update Before 7 August: Step-by-Step.

A Quick Note on Record-Keeping After Import

Importing your expenses into AffordableMTD satisfies the digital record-keeping requirement under MTD. But HMRC can still ask to see the underlying evidence - receipts, invoices, and bank statements - that support those figures. Keep those originals safe, either physically or as digital scans, for at least five years after the relevant tax return is filed.

The HMRC record-keeping standards that apply to MTD users are covered in HMRC Record-Keeping Standards for MTD: What You Must Keep.

Summary

Importing expenses via CSV is significantly faster than manual entry when you have a lot of transactions to record. Prepare your file with three columns - Date, Description, Amount - export it from your bank, upload it in AffordableMTD, and let the AI categorisation sort the bulk of your transactions. Then review the suggestions, correct anything flagged, add cash and mileage expenses manually, and do a final sense-check before you submit. With 24 days to the 7 August deadline, this approach gives you a realistic way to get your Q1 records in order without spending days on data entry.