ai-bookkeeper salestax return --state VA and --state AZ already gave the right date, by accident: the default for an unlisted state is the 20th. I made it deliberate, so a later change to the default cannot move them without a test failing.
- Virginia: the Tax Department's Form ST-9 instructions (July 2023 and later) say return and payment are due on the 20th of the month following the end of the period. Monthly or quarterly filing is assigned by the Department.
- Arizona: Transaction Privilege Tax returns are due the 20th; electronic filers get until the end of that month (not modelled, so the tool is early by design). Frequency follows estimated annual liability.
Both come from search excerpts, not the forms themselves, so check your own notice. Weekend and holiday dates roll to the next business day as for other states. See ventures/ai-bookkeeper/README.md.