So suppose your average profit over the three years they've been using was £20,000.
Your last grant @ the 80% rate would have been £4,000.
So in the last tax year, suppose you lost £4,000 profit because of Covid, and your profit was £16,000.
Your average over the four years would then be £19,000. Your grant @ 80% would be £3,800.
So you'd lose £200 for the three month grant @ 80%. Not good, but hardly a catastrophe.
And that's maybe a worse case scenario - I've assumed profits for the tax year to April 2020 are down 20% because of Covid, which is probably unlikely because lockdown only covered a couple of months.
In fact my profit for the last tax year was up slightly on the three-year average, so if my figures are correct my next grant will be about £12 higher
Anyway, all that's assuming they're averaging profits over the past four years rather than three.
And, of course, your profits for the last tax year could have gone up or down significantly for reasons other than Covid
