The relevant period is where SMP estimates stop being abstract. Payroll teams need a real earnings window, not a broad instruction to “look at recent pay.” BumpPay frames that window around the qualifying week and then lets the user enter the earnings data directly so the average weekly earnings basis stays visible instead of disappearing into code.
That matters because relevant-period mistakes are common. People often use a recent month because it is convenient, not because it matches the payroll rule they should be checking. The safer pattern is to identify the qualifying week first, then capture the pay in the relevant period using the cadence the user actually runs. Weekly and monthly payroll users still need the same logic, but the helper copy should speak their language.
A good result page does more than produce a number. It shows what period the estimate assumed, how the average weekly earnings were formed, and what to review if the pattern looks odd. If someone has irregular earnings, a payroll correction, or recent changes in hours, the next step is a manual review against the methodology page and the GOV.UK source note, not false certainty.