For generations, accounting firms have sold one thing above all else: time. Accountants record chargeable hours, utilisation drives performance, billings drive revenue, and partner economics are built around leverage.

AI breaks that equation. If an accountant can analyse financial data, research tax issues or prepare working papers in minutes rather than hours, what should the client pay? And who receives the productivity dividend — the accounting firm, the client or the employee?

Under time-based billing, there is an uncomfortable paradox. The more efficient the accountant becomes, the fewer hours there are to bill.

For decades that didn’t matter much. Spreadsheets, accounting software and offshore processing improved productivity incrementally. AI is different. It can collapse hours of professional labour into minutes.

This isn’t merely a pricing problem for KPMG, PwC, Deloitte and EY. Accounting firms have built entire organisational systems around time — utilisation targets, staffing, promotion, remuneration and partnership economics. Remove time as the organising principle and you potentially change the firm itself.

Fixed fees are one alternative. Subscriptions are another. Value-based pricing asks a more fundamental question: what was the advice actually worth?

A tax strategy that saves a client $2 million isn’t worth less because AI helped an accountant develop it in two hours rather than twenty. Indeed, greater efficiency should arguably increase the value proposition rather than diminish it.

AI isn’t eliminating accounting expertise. It is exposing something we’ve known all along. Clients don’t buy hours. They buy expertise, judgement and outcomes.

Perhaps the biggest disruption AI poses to the Big Four isn’t replacing accountants. It’s destroying the economic logic of the billable hour.