Microsoft 365 Copilot vs ChatGPT for Accounting Work (2026)

Microsoft covers Copilot prompts and responses under the same Data Protection Addendum and Product Terms that govern a firm's Exchange email and SharePoint files, and says prompts, responses, and the Microsoft 365 data Copilot reads are not used to train its foundation models. Copilot also honors existing permissions, sensitivity labels, retention policies, and audit settings. ChatGPT Business and Enterprise also exclude workspace data from training by default and add admin controls, which is a solid baseline. The edge goes to Copilot because the data never leaves a governance setup the firm already runs.

Copilot lives in the apps where accountants spend the day. It drafts and summarizes email threads in Outlook, recaps Teams meetings, and helps with formulas and analysis in the Excel workbook that is already open. ChatGPT can connect to Outlook, Teams, and SharePoint through its apps, once a Microsoft administrator grants permission, but the work still happens in a separate window. For everyday email and spreadsheet tasks, staying in the app wins.

Ask both tools the same hard question and ChatGPT usually gives the fuller, better organized answer. It is stronger at working through a complex client scenario, drafting a memo from rough notes, or explaining a technical point in plain language. Copilot's answers are often thinner on open-ended work. Neither is a tax authority, and both can invent citations, so verification is required either way.

Copilot in Excel has improved, but on messy real-world workbooks, such as a client's exported general ledger or a trial balance with inconsistent formatting, results can still disappoint. ChatGPT's file analysis handles uploaded spreadsheets, PDFs, and exports more flexibly, and can clean, reshape, and summarize data across several files in one session. The trade-off is that the file leaves Microsoft 365, so this only belongs on a business plan under firm policy.

Copilot's respect for permissions cuts both ways. It can surface any file a user already has access to, so a firm with loose SharePoint or OneDrive sharing can see sensitive client documents appear in answers to staff who should never have seen them. Cleaning up permissions before rollout is real work. ChatGPT only sees what a user uploads or connects, so the exposure is narrower and easier to explain in a firm policy, though the policy itself still has to be written and enforced.

Both are per-seat subscriptions with business tiers built for firms. Copilot is sold as the Microsoft 365 Copilot Business add-on on top of an eligible Microsoft 365 plan, or bundled in Microsoft 365 Business Standard with Copilot and Business Premium with Copilot. Eligible Microsoft 365 plans also include Copilot Chat at no extra cost, with enterprise data protection. ChatGPT offers ChatGPT Business, formerly Team, and ChatGPT Enterprise. Which costs less depends on what the firm already pays Microsoft, so neither wins outright.