Microsoft Copilot or a custom AI build: which do we need?
Buy Copilot or ChatGPT Business seats for general, personal work: writing, summarising, meetings and searching your own documents. Build custom AI when one repeated process runs on your own data across several systems, or when the people using it would never hold a seat, such as your customers. Most mid-sized companies end up with both, and the seats are the cheaper place to start.
Evidence
A seat is priced per person, every month, whether that person uses it once or all day. A custom build is priced by the work it does. Every week this site's citation tracker asks AI assistants the questions our clients ask, about 180 answers a run, and records which sources they cite. Its AI bill is read from production, not estimated.
- $0.54 to $1.10 per weekly run of the citation tracker
- About 180 AI answers collected and read per run
- 0 seats: one tool does the work for everyone, with no per-user fee
That is the shape of a good custom build: one process, done the same way every time, costing about the same however many people read the results.
What Copilot and ChatGPT Business seats do well
Off-the-shelf seats are the fastest way to put AI in front of your staff, and for a lot of work they are the right answer:
- Writing and editing. Drafting emails, proposals and reports, and tightening what a person wrote.
- Summarising. Long threads, documents and meeting recordings, turned into what was decided and who owes what.
- Inside Microsoft 365. Copilot works in Outlook, Word, Excel, Teams and SharePoint with the permissions your staff already have.
- One person's questions. Research, analysis of a spreadsheet, or a first draft of a plan, where a person reads every answer before using it.
On a business plan your company controls, neither trains on your data, and they are ready the day you buy them. Nothing has to be built.
Where per-seat pricing and generic workflows stop fitting
- Per-seat pricing grows with headcount, not with value. Each seat is a monthly fee per user. Multiply it by everyone who would touch one process, and you pay for a whole department to get one job done, including the people who open it twice a month.
- A generic assistant does not know your process. It answers what each person asks, in the way they happened to ask it. A process that should run the same way every time, such as reading every invoice into your accounting system, needs to be built once and then run, not re-prompted by each person.
- Your data lives in more than one system. Seats are strongest inside one suite. A workflow that reads from your ERP, writes to your CRM and checks your shared drive needs the connections built.
- The people using it would never hold a seat. Your customers, website visitors and suppliers cannot be given Copilot licences. An assistant that answers them has to be built.
A simple decision rule
- Buy seats when the work is general and personal: writing, summarising, meetings and questions, done by staff, mostly inside Microsoft 365.
- Build when it is one repeated process on your own data across your systems, or when it is used by people who would never hold a seat, such as customers or visitors.
- Do both when you have both kinds of work, which most mid-sized companies do. Seats for everyone's everyday work, and a build for the one process that costs the most time.
If you already have seats and nothing changed, the problem is usually the second kind of work being asked of the first kind of tool.
Next step
The AI Audit looks at your processes and tells you which ones seats already cover, and which one is worth building, with what it would cost to build and to run.