Build, buy or configure? Why 76% of enterprise AI is now bought, not built
A 2026 build vs buy AI analysis finds 76% of enterprise AI use cases were purchased in 2025, up from 53%, while in-house builds fell from 47% to 24%. For UK mid-market firms the question has become what thin custom layer is worth building.
3 October 2026
Searches for “build vs buy AI” are rising among UK mid-market firms, and the numbers behind them are stark. A 2026 analysis of enterprise AI spending reports that 76% of AI use cases were purchased in 2025, up from 53% in 2024. Internal builds fell from 47% to 24% in a single year.
The surprise in the data
You might read that and conclude custom software is dying. The same analysis points the other way: 35% of surveyed teams have replaced at least one SaaS tool with custom software, 78% of builders expect to build more in 2026, and 51% have shipped production AI software. Buying and building are both growing, because they are no longer the same decision.
The four buckets
The framework in circulation sorts every workflow into one of four groups:
- Buy it: common workflows with mature vendors, such as payroll or transcription.
- Configure it: platforms that get you most of the way with settings and connectors.
- Build it: workflows that depend on your own data or business rules.
- Leave it: rare or low-volume processes that do not justify automation.
The recommended pattern is layered: buy the model and assistant platform, configure it to your workflows, and build only the thin custom layer that encodes what makes your business different.
The cost most plans miss
Custom builds on bought models typically take around 90 days from start to production for a defined workflow. The same source warns that maintenance costs exceed initial development. A budget that only covers the build is the wrong budget.
Another figure should worry any CTO: 60% of teams report creating software outside IT oversight, and 25% do so frequently. Ungoverned building is the real risk, not building itself.
So what
Do not ask “should we build or buy AI?” Ask which of your workflows sit in the “build it” bucket, and whether the answer depends on data or rules a vendor cannot see. If the honest answer is a small number of them, you need a focused custom layer, properly maintained, not a platform. That is the work behind our custom software development service, and if you want to test a specific workflow against the four buckets, start a project.