A seat price is not the cost of the work

The Thomson Reuters Future of Professionals report for 2026 says 74 per cent of professionals use AI several times a week. It also says about a third use tools their organisation has not approved. In the corporate cut of the same research, unauthorised use was 36 per cent, and nearly three in five corporate tax and legal professionals said they were under pressure to move faster.

If the firm’s approved tool is not allowed to see the real file, the unapproved one is the personal account. The firm then pays for a system and still carries the risk of the system it refused to buy. That cost never appears as a software line.

Count the subscription for as many years as you expect to use it. Count the machines, and the person who keeps a local system running. Those costs are real, and they are higher at the beginning. We will not pretend otherwise, and we will not hand you a payback period. A single number, offered before anyone has looked at the practice, is a sales figure.

Then count the matters the rented tool cannot touch. Some clients already forbid their documents from being put into a third-party service. A cheap seat that is barred from those files is not a saving. It is a tool for the work that was never the sensitive work, which is often the work that earns the fees.

Then count the hour a lawyer spends again. A draft that is fluent and wrong, or a document whose formatting has been pulled apart, still has to be rebuilt. That hour exists on any system. It is smaller when the result comes back in the document itself, with the changes shown as track changes, instead of as a block of text the associate has to paste into a precedent and repair.

You are paying for a system that can take the client file, because the file is processed on the firm’s own machines. There is no second, personal tool for the matters the rented product is not allowed to see.

You are also paying for the firm’s own know-how to be usable on that file: precedents, playbooks, and the way the team already writes. A generic model does not have that, which is why so much of the “saved” time is spent correcting it. The correction is part of the cost. A system that starts from the firm’s own work spends less of the lawyer’s hour getting back to the firm’s standard.