How the weekly compensation check works
Two checks, both small on purpose.
The first takes the weekly earnings figure ACC based your compensation on, applies the statutory rate and the weekly maximum, and compares that with what you are paid. The second only runs if you are doing some paid work: compensation reduces so that earnings and compensation together do not exceed your pre-injury earnings, and that reduction is arithmetic that can be re-done from your own figures.
What a "does not reconcile" means
Usually not an error in anyone's arithmetic — most often the earnings figure ACC holds is not the one you expect, because of how the earning period fell or what counted as earnings. That is exactly why the next step is always the same: ask ACC to show the calculation. They must provide it, it costs nothing, and most questions end there.
What this check cannot see
Your ACC file, the earnings history ACC used, agreed rehabilitation arrangements, and the handful of special cases (seasonal patterns, multiple employers at injury, NZ Super interactions). Where your situation touches one of those, the honest answer is that this checker is too small for it — and it will say so rather than pretend.
Nothing you type leaves your device. There are no timeouts, and your answers keep while you find the letters.