Tax return season puts enormous pressure on practice capacity. There are no shortcuts on the technical work. The written work around it, the cover letters, information request emails, query responses, and client chasing, can often be made faster and more consistent.
This article is part of Runbook's complete guide to AI prompts for accountants. It focuses specifically on the written tasks that surround tax return preparation: the correspondence, queries, and documentation that consume a significant number of hours across every January and the months that follow. Each section includes prompts you can use immediately in ChatGPT, Microsoft Copilot, or Claude, along with notes on how to adapt them for your firm's context. If you want to know whether your practice is ready to build this kind of workflow, the free AI Readiness Scorecard will give you a clear picture in under five minutes.
Tax, legal and data protection disclaimer: These prompts are drafting aids only. They should not be used to calculate tax liabilities, determine tax treatment, provide tax advice, submit returns, or replace professional review. Any client-facing communication should be checked by a suitably qualified person against the client file, HMRC guidance, the firm's professional obligations, and the firm's data protection policy before being sent.
What AI can and cannot do in tax return work
It is worth being direct about the boundaries before getting into the prompts, because this is an area where misapplied AI creates genuine risk.
General-purpose AI tools such as ChatGPT, Claude and Copilot should not be relied on to prepare, calculate or file a Self Assessment tax return. They do not have access to HMRC systems. They cannot pull figures from accounting software, verify calculations, or apply current tax rates and thresholds reliably. If you ask one of these tools to calculate a client's tax liability, it may give you a figure that looks plausible but contains errors. That is not a safe use of these tools.
What AI tools can do reliably in tax return work is handle the written tasks that surround the technical process. Cover letters accompanying completed returns. Emails requesting information from clients before the return can be started. Polite but persistent chasing messages when a client has not responded. Clear explanations of what a tax calculation means and why the liability is what it is. These are high-volume, repetitive writing tasks where a well-constructed prompt consistently produces a usable first draft.
That distinction matters because tax return season is precisely when practice capacity is most stretched. The written work does not disappear during busy season; it expands. Getting faster at it without sacrificing quality is where AI earns its place.
Important: None of the prompts in this guide are designed to replace qualified professional judgement. The technical content of any communication, the figures, the tax position, the advice, must be verified by a qualified person before it reaches a client. AI is a drafting aid. The accountability remains with the accountant.
Tax return cover letter prompts
A covering letter for a completed Self Assessment return serves a specific purpose: it tells the client what you have done, what they owe or are owed, what they need to do next, and by when. The structure is consistent enough that AI handles it well once given the relevant figures.
Standard cover letter for a straightforward return
Use this prompt when the return is complete and you have the key figures to hand. Replace the bracketed sections with the actual details before sending the prompt.
Write a professional covering letter for a completed Self Assessment tax return. The client is [name or description, e.g. a sole trader electrician]. The tax year is [e.g. 2024/25]. Their tax liability is [amount]. Payment is due by [date]. They [do / do not] have payments on account due. The next step required from the client is [e.g. to review and approve the return before we submit]. Write in a clear, professional tone in British English. Keep the letter to three short paragraphs. Do not include any figures I have not provided.
The instruction at the end ("do not include any figures I have not provided") is important. Without it, some AI tools will insert plausible-looking figures that are incorrect. Always review the output against your actual workings before sending.
Cover letter where there is a refund
Refund letters require a slightly different structure: clients want to know when they will receive the money and whether any action is needed on their part.
Write a short covering letter for a completed Self Assessment return where the client is due a refund. The client is [description]. The tax year is [year]. The refund amount is [amount]. HMRC typically processes refunds within [timeframe, e.g. four to six weeks] of submission. No action is required from the client once they have approved the return. Write in British English, professional but warm in tone. Three short paragraphs maximum.
Cover letter where there is a higher than expected liability
This is the letter clients read most carefully, and the one where tone matters most. The prompt below gives the AI enough context to produce a draft that is factual without being cold.
Write a professional covering letter for a Self Assessment return where the tax liability is higher than the client may have expected. The key reason for the higher figure is [e.g. the inclusion of a one-off income item / a change in their trading income / the reduction in a previously claimed allowance]. The total liability is [amount]. Payment is due by [date]. The tone should be clear and factual without being alarming. Explain the main reason for the figure in plain English in one short paragraph. Do not include any figures I have not provided. British English throughout.
The AI Prompt Pack for UK Accountants includes a dedicated section on tax return correspondence, alongside prompts for client emails, management accounts, engagement letters, and more. Works with ChatGPT, Copilot, and Claude.
Client information request prompts
Before a return can be prepared, most clients need to provide information. Requesting that information clearly, specifying exactly what is needed and by when, reduces the back-and-forth that makes this part of the process inefficient. AI handles information request letters well because the structure is consistent and the main variable is the list of items required.
Annual information request for a Self Assessment client
Write an email to a client requesting the information needed to prepare their Self Assessment tax return for [tax year]. The client is [brief description, e.g. a director of a limited company with rental income]. The information we need from them includes: [list the specific items, e.g. P60 from their employer, dividend vouchers, rental income and expenditure figures, details of any asset disposals]. The deadline for receiving this information is [date]. Keep the tone professional and helpful. Use numbered formatting for the list of required items. British English throughout.
Follow-up request for a specific missing item
When a client has responded partially but one or two items are still outstanding, a targeted follow-up is more effective than resending the full list.
Write a short follow-up email to a client who has provided most of the information needed for their Self Assessment return but has not yet supplied [specific item, e.g. their bank interest summary or details of a property sale]. We need this item to complete the return. Our filing deadline is [date]. The tone should be polite but clear that this item is needed promptly. Two short paragraphs. British English.
Chasing and reminder prompts
Client chasing is one of the most time-consuming and morale-draining tasks in a practice during tax return season. The messages are similar each time; the volume is not. AI can handle the drafting of these messages consistently and without the fraying patience that can creep into the tenth version written from scratch on a Friday afternoon.
First reminder: information still outstanding
Write a polite first reminder email to a client whose Self Assessment information was due on [date] and has not yet been received. We originally contacted them on [date]. The filing deadline is [date]. We want to flag that we cannot begin the return without their information and that a late response may affect our ability to meet the deadline. Tone should be professional and non-confrontational. British English. Three short paragraphs.
Second reminder: more urgent tone
Write a second reminder email to a client whose Self Assessment information is now [number] weeks overdue. We have contacted them previously on [dates]. The HMRC filing deadline is [date]. At this stage we need to make clear that if we do not receive their information by [specific date], we may not be able to guarantee filing before the deadline, and they could face a late filing penalty. The tone should be firm but professional. British English. Keep it brief.
Post-submission confirmation and payment reminder
Write a short email to a client confirming that their Self Assessment return for [tax year] has been submitted to HMRC. Their tax liability is [amount], due by [date]. Explain that the client should pay using one of the current payment methods listed by HMRC and should allow enough time for the payment to reach HMRC before the deadline. Do not include any figures or payment details I have not provided. British English. Professional and reassuring in tone.
Query response and explanation prompts
Clients routinely ask questions about their tax return: why their liability is higher than last year, what a particular entry means, why payments on account are required. Answering these clearly and in plain English takes time. A well-constructed prompt gives you a solid draft to work from rather than a blank page.
Explaining payments on account
Payments on account are one of the most common sources of confusion for Self Assessment clients, particularly those new to the system.
Write a plain English explanation for a client who has received their Self Assessment calculation and is confused about payments on account. Explain that payments on account are advance payments towards the next Self Assessment bill, usually made in two instalments, each normally based on 50% of the previous year's relevant liability, due on 31 January and 31 July. Make clear that payments on account do not apply in every case, and that the client should check their actual HMRC calculation for the amounts that apply to them. Do not use jargon. Keep it to three short paragraphs. Do not state any specific figures. British English.
Explaining a year-on-year increase in liability
Write a short explanation for a client asking why their Self Assessment liability has increased compared to last year. The main reasons for the increase are [list the actual reasons, e.g. higher trading profit, loss of a previously claimed allowance, change in dividend income]. Write in plain English without jargon. The explanation should be factual and calm in tone. Do not fabricate reasons or include figures I have not supplied. British English. Three short paragraphs maximum.
Explaining the need for additional information
When a client questions why you need a specific piece of information, a clear and patient explanation saves a lengthy phone call.
Write a short email to a client explaining why we need [specific item, e.g. details of their foreign income / confirmation of their rental expenses / a copy of their P11D] to complete their Self Assessment return. The explanation should be clear and practical, not technical. Reassure them that this is a standard requirement and we need it to make sure their return is accurate. British English. Two paragraphs.
Building a prompt library for your firm: The prompts in this article work best when saved and shared as a team resource rather than used individually. A prompt library means everyone in the practice benefits from the same tested instructions, not just whoever is experimenting at any given moment. Our complete guide to AI prompts for accountants covers how to build and manage a prompt library for your practice.
A note on data protection before you use these prompts
The prompts above are written with placeholder text in square brackets precisely so that you have to actively substitute the real client details rather than copy-pasting a prompt that already contains them.
Before including identifiable client information in any AI prompt, your practice should have confirmed the lawful basis for processing, checked the provider's terms and data processing arrangements, assessed whether prompts or outputs are used for model training, applied data minimisation principles, and documented the use in your AI or data protection policy. A data processing agreement is an important part of that picture, but it is not the whole compliance position.
Do not assume that a free, consumer or unauthorised AI account is suitable for client data. Check whether the specific account, login type and product version are covered by your organisation's contractual terms, DPA, admin controls and data protection commitments. This matters in particular for Microsoft products, where protections can differ significantly depending on whether the user is signed in with a personal account or an organisational Microsoft Entra account.
Business and enterprise plans from providers such as OpenAI (ChatGPT Business or Enterprise), Microsoft Copilot products used through an organisational Microsoft 365 tenant, subject to the specific licence, admin settings and contractual terms in place, and Anthropic business plans, such as Claude Team or Enterprise, where appropriate contractual terms are in place are more likely to provide the contractual, security and data-processing protections a practice needs. However, you should verify the specific product, plan, terms, region, retention settings, training settings and admin controls before processing client data through any of them. If you are not certain what your practice is using, check before including client names, reference numbers, or financial figures in any prompt.
If your practice does not yet have a written policy covering which AI tools are approved and what data can be processed through them, that is the foundation on which everything else in this article should sit. Runbook's guide on how to write an AI policy for your accountancy practice covers what to include and how to structure a policy that is practical rather than a document nobody reads.
The prompts in this guide are most effective when your practice has made those foundational decisions: which tool, which account type, and what data can go in. Without that clarity, you will spend more time second-guessing each use than you save on the drafting itself.
Frequently asked questions
Can I use AI to prepare a Self Assessment tax return?
General-purpose AI tools such as ChatGPT, Claude and Copilot should not be relied on to prepare, calculate or file a Self Assessment tax return. They do not have access to HMRC systems, client financial data, or the real-time figures needed to complete a return. Where AI adds value in the tax return process is in the written work that surrounds the return: cover letters, client queries, chasing emails, explanatory notes, and follow-up communications. All technical preparation and filing remains the responsibility of a qualified professional.
Is it safe to include client details in AI prompts for tax work?
Before including identifiable client information in any AI prompt, your practice should have confirmed the lawful basis for processing, checked the provider's terms and data processing arrangements, assessed whether prompts or outputs are used for model training, applied data minimisation, and documented the use in your AI or data protection policy. Do not assume that a free, consumer or unauthorised AI account is suitable for client data. Check whether the specific account, login type and product version are covered by your organisation's contractual terms, DPA, admin controls and data protection commitments. If in doubt, do not include client-identifiable details, and consult a qualified data protection adviser if you do not yet have a policy in place.
Which AI tool works best for tax return correspondence?
ChatGPT, Microsoft Copilot, and Claude all handle tax return correspondence prompts reliably. The differences between them for this type of task are modest. The more important factor is the quality of the prompt rather than the choice of tool. A well-structured prompt will produce a usable draft in any of the three tools. If your practice already uses Microsoft 365, Copilot is a convenient starting point because it sits inside the applications you are already using.
Do I need to tell clients I used AI to draft their correspondence?
There is not currently a blanket UK rule requiring accountants to disclose every use of AI-assisted drafting. However, firms should consider disclosure where AI use is material to the service, affects client expectations, involves client data, or is addressed in the engagement letter, privacy notice or AI policy. In all cases, professional judgement, confidentiality, accuracy and review obligations remain with the practice. AI-assisted drafts still need human review before being sent.
How do I get better results from AI prompts for tax work?
The single biggest improvement comes from giving the AI more context. Instead of asking for a cover letter, tell the AI the client's situation, the key figures, any unusual circumstances, and the tone you want. The more specific the prompt, the less editing the output requires. Starting with a tested prompt from a structured library rather than writing from scratch also reduces the time spent on iteration.