Provisional Acceptance Testing (PAT) is a conditional, interim form of acceptance. It allows a system to be accepted provisionally — often so it can go into use or trigger a contractual milestone — while some agreed items remain outstanding and are tracked to completion.
How PAT typically works
- The system meets the core criteria and is accepted provisionally.
- A list of outstanding items (minor defects, pending features) is agreed.
- A timeframe and conditions for final acceptance are set.
- Once the outstanding items are resolved, final acceptance follows.
Provisional to final acceptance
Why it exists
PAT is a pragmatic compromise: it lets a largely complete system deliver value without waiting for every last item, while still holding the supplier accountable for finishing the job. The risk is that "provisional" quietly becomes permanent if the outstanding items are not tracked firmly.
Conclusion
PAT provides a conditional, milestone-friendly acceptance for large contractual projects, bridging the gap between "good enough to use" and "fully complete". It is uncommon in typical software work, but valuable to understand where formal, staged delivery applies.