Final Acceptance Testing (FAT) is the definitive confirmation that a system fully meets its agreed acceptance criteria and is complete. Where provisional acceptance is conditional, final acceptance is unconditional — it is the formal statement that the delivery is done and accepted.
What FAT confirms
- All agreed acceptance criteria are met.
- Any items outstanding from provisional acceptance are resolved.
- The system performs correctly in real-world conditions.
- The customer formally signs off and takes ownership.
The road to final acceptance
UAT passed
→
Outstanding items closed
→
Final acceptance & sign-off
Why it matters contractually: final acceptance often marks the transfer of ownership, the start of warranty or support terms, and — in commercial projects — final payment. Clear criteria make this milestone unambiguous.
Conclusion
FAT is the final, unconditional gate: every criterion met, every outstanding item closed, and formal sign-off given. It turns "nearly done" into "accepted and complete", with all the contractual weight that carries.