“How often should we run a penetration test?” is one of the most common questions we hear, and the honest answer is: it depends. That is not a dodge — the right cadence genuinely varies from one organisation to the next — but the factors that decide it are entirely straightforward, and there are sensible baselines to work from once you understand them. Anyone who gives you a single universal number without asking about your systems is guessing.
What drives the cadence
- Risk. The more sensitive your data and the more exposed your systems, the more frequently you should test. A public-facing platform handling financial or health data warrants markedly more attention than an internal tool with limited reach and low-value data.
- Change. Significant changes — a new application, a major release, a re-architecture, a migration to the cloud — introduce new risk and warrant testing regardless of where you happen to be in the calendar. Attackers do not politely wait for your annual cycle, and neither should your testing.
- Compliance. Frameworks such as PCI DSS, ISO 27001 and various regulatory regimes set their own expectations for testing frequency, which may establish a floor you are simply obliged to meet.
Sensible baselines
For most organisations, a good rhythm looks like this: a penetration test at least annually for important systems, plus a test after any major change, with regular vulnerability scanning filling the gaps in between. The logic is sound and worth internalising: scanning is cheap, fast and continuous, making it ideal for catching known issues as they appear, while penetration testing is deeper and periodic, giving you the human-led assurance that scanning fundamentally cannot. You want both working together, layered, not one standing in for the other.
Think in layers, not a single number
The most useful mental model is layers of assurance rather than a single magic frequency. Continuous scanning provides ongoing hygiene and catches the obvious. Periodic penetration testing provides depth and finds what tools miss. Change-triggered testing catches new risk at exactly the moment it is introduced, before it has time to be discovered by someone less friendly. And for mature organisations, occasional red teaming tests whether you would even detect a real, careful attacker. The exact numbers fall out naturally of your risk profile and obligations once you think in these terms rather than searching for one universal answer.
Do not forget the re-test
A test that finds issues is only half the job done, and this is the step organisations skip most often. Budget for a re-test after remediation to confirm the fixes actually worked — an open finding is not truly closed until it has been independently verified. Skipping this means organisations sometimes carry risk they sincerely believe they have already eliminated, which is arguably worse than knowing the risk is there. Treat remediation and verification as an integral part of the engagement, not an optional extra to be dropped when budgets tighten.
Think of it as layers: continuous scanning for hygiene, periodic penetration testing for depth, and an extra test whenever something important changes — with a re-test to confirm fixes actually landed. The exact frequency follows naturally from your risk and your obligations.
The takeaway
There is no universal “test every X months” answer, and treating penetration testing as a single annual box to tick misunderstands what it is for. Set a sensible baseline — at least annually, plus after major change — layer continuous scanning underneath it, always verify your fixes with a re-test, and adjust the cadence upward as your risk and obligations demand. Do that, and your testing programme genuinely tracks your risk rather than merely satisfying a calendar.