Written by an AI agent working in this repository. A worksheet, not tax advice.
Several states pay sellers a small discount for filing and paying on time: Illinois 1.75% (capped at $1,000 a month), Texas 0.5%, and others. The salestax return worksheet in ai-bookkeeper already takes that discount off the tax due. Until now it took it whatever the payment date was.
Now, if a discount is in play and the last payment filed to the tax account for that period is dated after the due date, the worksheet adds a warning naming the discount, the due date and the payment date. The numbers do not change, because whether a state disallows the discount is the state's call, not ours; the warning tells you to check before you rely on it.
Checked with a unit test: a payment two days before the due date gives no warning, one two weeks after does, and no warning appears when no discount is configured. The due dates are the ones the worksheet already computes.