The sales team tab in an account allows you to set a commission structure on an account.
You can set a start and end date on the commission.
Rate is as a decimal ie 20% will be 0.20
You can set a max payment
Also that you do not pay a commission unless the invoice is above or below a particular value.
So in the below example, Paul is receiving 20% for all of 2020 up to a maximum of £500 per customer invoice.
Then from 2021 onwards 10% upto a maximum of £500 per customer invoice, however, the invoice must be over £100