User acceptance testing (UAT)
User acceptance testing is the final test phase in which business users check that a new or changed system supports their real processes and meets the agreed requirements and acceptance criteria. Formal UAT sign-off is usually a condition for go-live.
Roles that need it
What it is
User acceptance testing (UAT) is the test level where the people who will use a system confirm it is fit for their work. Earlier levels check the software from a technical angle: unit testing checks components, and system integration testing (SIT) checks that systems exchange data correctly. UAT asks a different question: can a payments operator, a reporting analyst or an accountant do their job with it, end to end, using realistic data?
A UAT phase normally has a test plan, entry criteria (for example SIT complete and no open critical defects), test scripts written from requirements and acceptance criteria, a test environment with production-like data, a defect log and exit criteria. It ends with a formal sign-off by the business owner.
Why it matters
UAT is the last chance to catch problems before customers, regulators or the ledger are affected. A system can pass every technical test and still fail in use: a screen may need ten clicks for a task done a hundred times a day, or a report may sum the right fields with the wrong sign. In regulated firms, test evidence and sign-off also support change management controls, and DORA (the Digital Operational Resilience Act) requires ICT changes to be tested and approved before deployment.
Worked example
Illustrative numbers. A regulatory reporting tool upgrade has 120 UAT scripts. In the first cycle, 96 pass and 24 fail, a pass rate of 80 percent. The 24 failures produce 30 defects: 2 critical, 8 high, 20 medium or low. Exit criteria require zero open critical or high defects and at least 95 percent of scripts passed. After fixes and a second cycle, 116 scripts pass (96.7 percent). The 4 remaining failures relate to low defects with agreed workarounds, so the business owner signs off and the go-live goes ahead.
Who uses it
Business analysts write or review test scripts and trace each one to a requirement. Project managers and PMO analysts plan UAT cycles, track pass rates and report defects to the steering committee. Product owners confirm stories meet their acceptance criteria. Subject matter experts such as regulatory reporting analysts execute scripts with real scenarios and decide whether results are correct. Testers coordinate environments and evidence.
Common confusions
UAT is often treated as a repeat of SIT run by different people. Its scope is business fitness, so scripts should follow real processes, including exceptions and month-end peaks. Another confusion is to let the delivery team sign off UAT on behalf of the business: acceptance only has value when the accountable business owner gives it. Finally, UAT does not replace regression testing; existing functions also need to be retested after changes.