A remote seller must collect Iowa sales tax and local option sales tax only if it has $100,000 or more in gross revenue from Iowa sales (as at 1 October 2026). The transaction-count test was eliminated from 1 July 2019. A seller with several locations, all outside Iowa, adds up its sales into Iowa from all of them.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.