ChatGPT vs Microsoft Copilot for UK Accountants: Which Is Right for Your Practice?

Two tools come up in almost every conversation UK accountancy practices are having about AI in 2026: ChatGPT and Microsoft Copilot. They are not the same tool doing the same thing, and choosing between them based on name recognition alone means a lot of practices are paying for the wrong one.

This article is part of Runbook's complete guide to AI tools and software for UK accountancy practices. What follows is a direct, use-case-by-use-case comparison of ChatGPT and Microsoft Copilot, including pricing in GBP, data protection considerations under UK GDPR, and a clear verdict on which tool suits which type of practice. If you want to know whether your practice is ready to adopt either tool, the free AI Readiness Scorecard gives you a personalised picture in under five minutes.

What each tool actually is

The first thing worth being clear about is that ChatGPT and Microsoft Copilot are fundamentally different products, even though both use large language model technology and can both help you draft an email.

ChatGPT

ChatGPT is an AI assistant made by OpenAI, accessed through a browser or app. By default it operates as a standalone conversation interface: you provide context, it responds. The quality of what it produces depends heavily on the quality of what you ask it. On a paid Business plan, it is one of the most capable general-purpose AI assistants currently available, with strong performance on written tasks, research, summarisation, and complex drafting.

For most users the default experience is standalone, meaning ChatGPT does not automatically know what is in your Outlook inbox, your Word documents, or your client files. However, ChatGPT Business now supports connectors that allow it to connect to external sources such as SharePoint, Google Drive, Slack, and GitHub, which can reduce the need to manually copy content across. That said, even with connectors, this is a different experience to Copilot's native embedding inside Microsoft 365. The integration depth and workflow convenience are not equivalent.

Microsoft Copilot

Microsoft's AI offering is not a single product. It spans a range of experiences at different price points and with meaningfully different capabilities, which makes the comparison with ChatGPT more complicated than it first appears. The three versions most relevant to UK accountancy practices are:

Consumer Copilot (free): The Copilot experience available via Bing, Edge, and Microsoft's consumer apps. This is a general-purpose AI assistant aimed at individual users, not business use. Its data handling arrangements are consumer-grade and it does not carry the enterprise protections that professional use requires.

Microsoft 365 Copilot Chat: A chat-based AI experience available to Microsoft 365 Business subscribers at no additional per-seat cost (subject to eligibility and how licences are configured). It operates within Microsoft's commercial data boundary, meaning Microsoft commits that this tier does not use your data to train foundation models. For eligible business users this is a meaningful step up from the consumer product in terms of data governance, though the feature set is more limited than the full paid add-on. Whether this tier is appropriate for your firm's client-related work depends on your configuration and contractual setup, and should be assessed against your specific data protection obligations.

Microsoft 365 Copilot (paid add-on): The full AI layer embedded directly into Outlook, Word, Excel, Teams, and PowerPoint. It can read and act on content already in those applications: summarising an email thread, drafting a reply using context from your existing correspondence, or pulling key points from a Word document you have open. This is the version most relevant when people refer to "Copilot for work." It requires a qualifying Microsoft 365 subscription plus the paid add-on.

This article's use-case comparison focuses primarily on the full paid Microsoft 365 Copilot add-on, since that is what delivers the deepest integration. Where the distinction between tiers matters for a specific point, that is noted.

How they compare on common accountancy tasks

The most useful way to compare the two tools is not on headline features but on the tasks that actually fill the working week in a UK accountancy practice. Here is an honest assessment of each.

Client email drafting

Both tools are capable of drafting professional client emails in British English. The full Microsoft 365 Copilot add-on does it inside Outlook, which means no context-switching and the ability to reference your existing thread. ChatGPT's default experience involves working in a separate window, though on Business plans connectors to external sources can reduce the need to copy content manually.

For routine correspondence such as information request letters, appointment confirmations, and standard query responses, the difference in output quality is small. For more nuanced communications where tone and context matter, ChatGPT's flexibility and the ability to give it a detailed brief tends to produce better first drafts. For teams that have invested in developing good prompts, the gap narrows further. The Runbook guide to ChatGPT prompts for UK accountants includes a dedicated section on client communication with prompts that work with both tools.

Meeting notes and summarisation

For meeting transcription and summarisation within Teams, Copilot is the stronger option. It can generate a structured summary of a Teams meeting automatically, without requiring you to copy a transcript anywhere. The output quality is reliable and the workflow is frictionless for practices that run client meetings through Teams.

ChatGPT can summarise a transcript if you provide one, and will produce a well-structured result, but the additional step of obtaining and supplying the transcript reduces the time saving considerably compared to Copilot's native workflow. If meeting summarisation is a priority use case and your practice uses Teams, this is one area where Copilot's integration advantage is most tangible.

Document drafting and editing

For drafting and editing documents in Word, the full Copilot add-on can work directly within an existing document, which is useful for tasks like rewriting a section, expanding an outline, or summarising a long report. ChatGPT's default workflow produces content that then needs to be moved into Word, though Business plan connectors can reduce that friction where SharePoint or OneDrive is in use.

For document creation from scratch, where you are providing a brief and asking for a first draft, ChatGPT's output quality is generally ahead of Copilot's. Copilot is at its strongest when it has an existing document to work with; ChatGPT is at its strongest when generating from a clear set of instructions.

Research and regulatory queries

Both tools can help with internal research tasks: explaining a tax provision in plain English, summarising HMRC guidance, or providing a framework for approaching an unfamiliar area before a qualified accountant does their review. Neither tool should be treated as a source of authoritative technical advice, and all output should be verified against primary sources before use.

ChatGPT with web browsing enabled (available on paid plans) can retrieve and summarise current information, which is useful when you need to check a figure, look up recent guidance, or summarise a publication you do not have time to read in full. Copilot's external research capability has improved and it can also draw on current web information, but ChatGPT remains the more flexible tool for broader, open-ended research and synthesis where you want to combine sources, explore a topic, or work through an unfamiliar area in depth.

Spreadsheet and data work

Copilot in Excel can analyse data, generate formulas, and create summaries directly within a spreadsheet, which gives it a clear advantage for practices that use Excel heavily for management accounts, cashflow models, or client reporting. You can describe what you want in plain English and Copilot will suggest formulas or restructure data without you needing to know the syntax.

ChatGPT can help with Excel formulas and data analysis if you describe the problem or paste in a sample dataset, but it cannot interact with a live spreadsheet directly. For Excel-heavy workflows, Copilot is the more practical choice.

Side-by-side comparison

Pricing: what you will actually pay

Both tools have tiered pricing, and the tier matters for both capability and data governance. Pricing changes regularly, so the figures below are approximate at the time of writing. Always check the vendor's current pricing pages before making a decision.

ChatGPT pricing

ChatGPT Free: Available at no cost. Does not include a data processing agreement. Suitable for testing and for tasks that involve no client or sensitive information. OpenAI may use inputs from free accounts to improve its models.

ChatGPT Plus: At the time of writing, Plus is in the region of £16 per user per month, though OpenAI's pricing changes periodically and current GBP figures should be confirmed on their pricing pages. Includes access to more capable models and web browsing. Does not include a data processing agreement for business use. Not recommended for client-related work.

ChatGPT Business: Priced above Plus. For firms considering client-related use, this is the minimum tier worth evaluating, as it includes a data processing agreement and a commitment that your data is not used for model training. It also supports connectors to external business tools including SharePoint, Google Drive, Slack, and GitHub. Check OpenAI's current pricing pages for up-to-date GBP figures before budgeting.

ChatGPT Enterprise: Custom pricing negotiated directly with OpenAI. Designed for larger organisations with higher usage volumes and additional compliance requirements.

Microsoft Copilot pricing

Consumer Copilot (free): Available at no cost via Bing, Edge, and consumer Microsoft apps. Consumer-grade data handling. Not appropriate for professional use involving client information.

Microsoft 365 Copilot Chat: Available to eligible Microsoft 365 Business subscribers at no additional per-seat cost (subject to licence configuration). Operates within Microsoft's commercial data boundary. Capability is more limited than the full paid add-on, but it may be a practical starting point for practices that want to explore Microsoft's AI offering without additional spend. Whether it is suitable for client-related work depends on your firm's configuration, contractual setup, and data protection assessment.

Microsoft 365 Copilot (paid add-on): Approximately £25 to £30 per user per month at the time of writing, as an add-on to a qualifying Microsoft 365 subscription. This is in addition to your existing Microsoft 365 fees. For a practice of five people, the add-on cost is in the region of £125 to £150 per month on top of existing subscription costs.

A qualifying Microsoft 365 subscription is required before the paid Copilot add-on can be purchased. If your practice is not already on an eligible plan, check Microsoft's current requirements before budgeting for the add-on.

Data protection and UK GDPR

This is the question that most UK accountancy practices need to work through before deploying either tool for client-related work. The obligations are real, and how well a particular product tier addresses them varies more than vendor marketing tends to suggest.

What you need to consider

Under UK GDPR, if you are inputting personal data about clients (names, financial information, correspondence) into an AI tool, you are sharing that data with a third-party data processor. This means you need to be satisfied that: you have an appropriate legal basis for that sharing; the provider's contractual terms include the data protection commitments required under UK law; and your data is not being used for purposes beyond what you have disclosed to your clients, including model training.

Consumer and free tiers of most AI tools are not designed for this use case. They typically operate under consumer terms that do not include the governance controls a professional services firm needs. Before using any AI tool with client information, the right starting point is to review the provider's data processing terms, understand how your data is handled at your specific plan level, and assess that against your firm's data protection obligations. Where there is any doubt, take qualified legal advice before proceeding.

ChatGPT and UK GDPR

ChatGPT Business and Enterprise plans include a data processing agreement and a commitment that customer data is not used to train OpenAI's models. This makes them more suitable for professional use than the free or Plus tiers, subject to your review of the specific terms and your firm's obligations. The free and Plus tiers do not include these commitments and should not be used for client-related work without careful assessment of the data governance implications. The Business plan is the minimum tier worth evaluating for client-related use.

Microsoft Copilot and UK GDPR

Microsoft's data governance position is more layered than its competitors' because it spans multiple product tiers with different protections. The consumer Copilot experience carries consumer-grade terms and is not designed for professional use involving client data. Microsoft 365 Copilot Chat, available to eligible Microsoft 365 Business subscribers, operates within Microsoft's commercial data boundary and Microsoft does not use this data to train its foundation models. The full paid Microsoft 365 Copilot add-on operates under Microsoft's Products and Services Data Protection Addendum, which is designed to be compatible with UK GDPR.

The practical implication for most UK practices is that if you already hold a Microsoft 365 Business subscription, you may already have access to a tier of Microsoft AI that carries enterprise data protection commitments, depending on your licence configuration. Whether that tier is appropriate for your specific use of client data should be assessed against your firm's data protection obligations and the terms of your Microsoft agreement. It is not automatic clearance, but it is a more nuanced picture than a simple paid versus free distinction.

Where each tool falls short

Both tools have genuine limitations that are worth understanding before committing to either. The marketing around both products tends to emphasise capability; what follows is a more honest account of the gaps.

Where ChatGPT falls short

Integration depth does not match Copilot for Microsoft 365 users. While ChatGPT Business now supports connectors to tools such as SharePoint, Google Drive, Slack, and GitHub, the default experience is still a separate window with no automatic awareness of your existing email, documents, or client files. Even with connectors enabled, the workflow integration is not equivalent to Copilot sitting inside Outlook or Word. For practices that want AI embedded in their day-to-day Microsoft 365 tools, ChatGPT remains a less natural fit.

Output consistency requires good prompting. ChatGPT's output quality is highly sensitive to prompt quality. A vague or poorly structured prompt produces a generic result; a detailed, specific prompt produces a genuinely useful draft. Developing that prompting skill takes time and requires the team to invest in learning how to use the tool effectively. Practices that deploy ChatGPT without any guidance on how to prompt it tend to get disappointing results and abandon the tool early.

Context needs to be provided each time. ChatGPT's memory and persistence features have evolved, but the practical reality for most users is still that you need to provide relevant context for each task: details about your practice, the client, the situation. For simple tasks this is manageable. For complex or recurring work, building good prompt habits and templates is what separates effective users from frustrated ones.

Where Microsoft Copilot falls short

The full integration requires the paid add-on and a qualifying subscription. Microsoft's tiered lineup means the experience varies considerably depending on which version your practice is using. The free consumer Copilot is not a viable professional tool. Microsoft 365 Copilot Chat has meaningful data governance protections but limited functionality compared to the paid add-on. The full workflow integration (Copilot inside Outlook, Word, Teams, and Excel) only comes with the paid add-on, which requires both a qualifying Microsoft 365 subscription and an additional per-user fee. For practices that are not already on an eligible Microsoft 365 plan, the total cost of getting to that point is higher than a simple per-user add-on figure suggests.

Output quality for standalone writing is a step behind. When used for tasks that do not involve reading existing Microsoft 365 content (writing from a brief, researching a topic, producing a report from scratch), Copilot's output quality is generally a step behind ChatGPT. It is capable, but it does not match ChatGPT's flexibility or the nuance of its best outputs for open-ended written tasks.

The per-user cost is higher. At approximately £25 to £30 per user per month for the paid add-on, Copilot is a meaningful ongoing cost for a practice of any size. For a firm of eight people, that is in the region of £200 to £240 per month in addition to existing Microsoft 365 fees. The business case is clear for heavy Microsoft 365 users, but for teams that only dip into Outlook and Word, the cost relative to benefit deserves scrutiny before committing.

It is less useful outside the Microsoft 365 workflow. Copilot is designed to work within Microsoft 365, which means it is less useful for tasks that fall outside that context. Ad hoc research, complex custom prompts, or tasks that require generating content from a blank brief are areas where ChatGPT's flexibility gives it a clear edge.

Which tool is right for your practice

There is no single correct answer, and the two tools are not mutually exclusive. But most practices will have a clearer primary choice based on their existing setup and the tasks they most want to address.

Choose Microsoft Copilot if

• Your practice runs Microsoft 365 and your team spends the majority of its day in Outlook, Word, Teams, and Excel.
• Reducing context-switching and keeping AI inside existing tools is a priority, particularly for client email drafting and meeting summarisation.
• You want to start with Microsoft 365 Copilot Chat (available to eligible Microsoft 365 Business subscribers at no additional cost) before committing to the full paid add-on.
• You already have a qualifying Microsoft 365 subscription and the data governance terms are already reviewed and in place.
• Excel-based work (management accounts, cashflow modelling, client reporting) is a significant part of your team's time and you want AI embedded directly in spreadsheets.

Choose ChatGPT if

• Your practice does not run Microsoft 365, or does not use it heavily enough for Copilot's integration advantage to materialise.
• You want the most capable general-purpose AI assistant for written tasks, research, and complex drafting, particularly where output quality and flexibility matter.
• Your team is willing to invest time in developing good prompting habits, which will significantly increase the value they get from the tool.
• You are evaluating AI tools before committing to a long-term platform and want the tool with the broadest capability for a lower per-user cost.
• External research and summarisation of documents outside Microsoft 365 are regular requirements.

Consider using both

A number of practices in 2026 are using both tools for different purposes: Copilot for the day-to-day workflow inside Microsoft 365, and ChatGPT for more complex or open-ended tasks that benefit from its greater flexibility. At business-tier pricing, the combined per-user cost of both tools is meaningful, so the case for running both is strongest where each is being used consistently for distinct tasks rather than as a fallback. For most practices starting out, the cleaner approach is to pick one, develop a consistent workflow, and evaluate after three months before adding a second tool.

If you are not yet sure which use cases are most relevant to your practice, the free AI Readiness Scorecard identifies where your practice stands and which tasks are the most practical starting points. The AI Implementation Checklist then gives you a step-by-step process for rolling out whichever tool you choose, including data protection sign-off, staff guidance, and a 90-day adoption plan.

Frequently asked questions