The ones we purchased last month had an expiration date of Sept. 30, 2021 on the box. There is a notice on the label that the expiration date is extended 3 months past the expiration date, so that would be Dec. 31, 2021. Here is a link to lot numbers for expiration dates.

https://coronavirus.ohio.gov/static/binax-now/COVID-19-Ag-Card-Product-Expiry-Update.pdf
https://www.tchd.org/DocumentCenter/View/9226/Expiry-date-extension-regarding-BinaxNOW-COVID-19-Ag-Card-Home-Test?bidId=#:~:text=On%20April%206%2C%202021%2C%20the,additional%20three%20(3)%20months.