Chatbot, Calculator, or Liability? Free AI Meets the 31 January Tax Deadline

Deadline anxiety has a new assistant. With the self-assessment return for the 2025–26 tax year due by 31 January 2027, plenty of sole traders and side-hustlers are wondering whether a free chatbot can do the dull parts: sorting receipts, totting up expenses, explaining payments on account, maybe even estimating the tax bill. I tried the free tiers of several mainstream chatbots on a deliberately messy set of fictional sole-trader records. The short answer: they can save you an afternoon of admin. They can also invent a tax rule with total confidence. Treat them as an eager intern, not an accountant.

What I asked the free AI to do

The test was simple enough to be realistic. I created a fictional side-hustle: £18,000 of sales, a shoebox of 60 receipts, a mix of business and personal spending, some equipment, a bit of travel, and a home broadband bill. I then asked the bots to categorise the receipts, draft an expense summary, explain the trading allowance, and estimate the tax position. I also asked them to tell me what records HMRC expects and to flag anything they were unsure about.

The free versions were fine at the first two jobs. They were shakier on the third and fourth. The pattern was consistent: chatbots are good at turning mess into structure, and bad at knowing the limits of their own knowledge.

Where free AI genuinely helped

Receipt triage was the clear win. Uploading a spreadsheet or typing in a messy list and asking for columns such as date, supplier, amount, category and evidence produced a decent first draft. One tool spotted duplicate entries. Another turned a paragraph of notes into a workable expense table. None of this was magic, but it was quicker than starting with a blank spreadsheet.

It was also useful for plain-English explanations. Asking 'what is a payment on account, in simple terms?' produced a better answer than asking 'calculate my tax'. The bots were happier explaining jargon than doing arithmetic. That is exactly how I would use them: as a translator and organiser, not as a tax calculator.

A prompt such as 'ask me for missing information before you answer' improved the output noticeably. It forced the bot to check whether I had included business-use percentages, dates and whether an item was capital or revenue spending.

Where it got dicey

The failures were not subtle. One bot confused the trading allowance with the personal allowance. Another suggested claiming a proportion of broadband without asking whether I worked from home or ran the business from a phone. A third treated a lunch receipt as a business expense because it appeared in the same folder as a client invoice. None of these would necessarily survive a human review, but that is the point: the human review is not optional.

Prices, rates and thresholds change. Free chatbots may be working from older information, or may simply guess. They cannot know your exact circumstances, and they do not carry professional indemnity insurance. HMRC is not interested in whether a chatbot sounded confident. It is interested in whether the return is accurate and whether you took reasonable care.

There is also a data problem. Free tiers often have different privacy terms from paid accounts. Do not paste your National Insurance number, Unique Taxpayer Reference, bank details or full client list into a free chatbot unless you have checked how that data is handled. Anonymise the numbers. Use a test file. Keep sensitive identifiers out of the chat.

The human checks you must never skip

• Reconcile the AI summary against bank statements and receipts. If the totals do not match, fix the human records, not the chat.
• Check the tax year. A return due on 31 January 2027 covers the 2025–26 tax year, not the current one.
• Confirm whether you are using the £1,000 trading allowance or claiming expenses. You cannot simply claim both for the same income.
• Check eligibility before claiming anything. A bot can suggest a category; it cannot decide whether the expense is allowable for your business.
• Look for duplicates, personal spending and missing receipts. AI is good at patterns, not at knowing that a Tesco run was actually your weekly shop.
• Review payments on account and any student loan repayments separately. These are easy to overlook when a chatbot is busy producing a neat table.
• Save a copy of the final figures and the evidence. Do not rely on a chat history as your audit trail.
• If your affairs are complicated — property income, foreign income, VAT, crypto, multiple businesses — speak to an accountant. A free chatbot is not a substitute.

HMRC's late-filing penalties start at £100 and can climb. That is before interest and any compliance checks. The cost of getting a return wrong is not just the tax; it is the time spent sorting out the mess.

A prompt that behaved better

The most useful prompt I tried was not clever. It was cautious. I asked the bot to produce a table with date, supplier, amount, suggested category, evidence and confidence. Then I asked it to list every assumption it had made and every item it could not verify. That final instruction was the difference between a useful draft and a confident guess.

I would add one more line for anyone doing this for real: 'Do not calculate my tax liability. Give me a checklist of figures to verify with HMRC guidance or an accountant.' That keeps the bot in its lane.

The verdict

Free AI is a decent admin assistant for self-assessment. It can organise receipts, draft summaries and explain the vocabulary. It cannot sign your return, apply reasonable care on your behalf, or absorb the penalty if something goes wrong. Use it to make the boring bits faster, then do the human checks. At FreeAI.uk, that is the rule we keep coming back to: useful tool, final answer not included.

This article is general information, not tax advice. Check current HMRC guidance or speak to a qualified adviser about your own circumstances.