Hawaii's general excise tax return is due the 20th of the month after the period, and semiannual filers use the Jan-Jun and Jul-Dec halves. AI Bookkeeper's worksheet already produced those dates (July 20 and January 20), but a code comment said they were not modelled. The comment is fixed and a test now pins the two dates.
The evidence is one 2026 third-party guide and the history of a 2009 bill that moved the due date from month end to the 20th. The statute (HRS 237-30) and the Department of Taxation site were not read, so check your own notice before filing.