In brief
The new CoCounsel can write and run code for multistep tax, audit and accounting work.
It can build Excel workbooks with live formulas, assumptions and cited source material.
The accountant remains responsible for reviewing the output, especially when a workflow changes or source data is incomplete.
Accounting AI just moved past the chat box.
Thomson Reuters says its newest CoCounsel can write code, run calculations and build the actual files a professional would review. That includes multi-tab spreadsheets, Word memos, PDFs and workpapers based on a firm's templates.
Here's the thing: the pitch is no longer about using AI only to explain the work. The tool now does the first version of the work.
A spreadsheet is more useful than a paragraph
The system can handle calculations such as depreciation, amortization, required minimum distributions, qualified business income and threshold tests. It can also compare scenarios and update documents when the underlying facts change.
During a product demonstration, CoCounsel read a commercial real estate loan agreement and built an amortization workbook for a $5 million loan. The file included a loan summary, a full payment schedule, a balloon-payment calculation and follow-up notes.
The formulas stayed live inside Excel. Behind the scenes, the system also recalculated the result in Python and compared the two answers.
That second calculation is important. It gives reviewers another check instead of asking them to trust a polished spreadsheet because it looks finished.
The tool can fix itself, but that is not the same as being right
The demonstration showed the agent finding a problem in the schedule, rebuilding it and verifying the corrected values. That is useful behavior. It is not a substitute for professional review.
An AI system can make a consistent mistake if it starts with the wrong fact, applies the wrong authority or misunderstands the client's situation. A clean workbook can hide a bad assumption better than a messy draft can.
Thomson Reuters says CoCounsel Tax & Audit is grounded in current professional content and provides citations. The product page cites sources that include the IRS, FASB, GASB, AICPA and IFRS material.
The review job is getting bigger
This kind of tool changes where human time goes. Staff may spend less time copying numbers and building schedules. Reviewers may spend more time checking inputs, assumptions, formulas and authority.
Firms will need to decide what evidence belongs in the file when an agent writes code. That may include the source documents, prompts or instructions, the generated workbook, exception logs and the reviewer's signoff.
The old control was often a second person redoing part of the calculation. The new control may be a mix of independent recalculation, source tracing and a clear threshold for when a human must take over.
This is a workflow product, not a magic answer machine
CoCounsel can connect to other systems through the Model Context Protocol and integrates with Thomson Reuters products including UltraTax and Engagement Manager. That gives it more context and more places to act.
It also creates more risk if access is too broad. Firms should limit what the agent can read, change and export, then test those limits before putting client data into a new workflow.
The useful question is no longer whether AI can draft an email. It is whether a firm can review an AI-built workpaper as carefully as a human-built one, without quietly turning speed into blind trust.
