AACA requires a valid PA tax ID number to rent a space. Thus, all vendors (space owners) must report sales twice a year and pay tax on the amount reported. Whether the vendor explicitly charges a tax at the time of sale is irrelevant, the vendor is liable for paying the tax. The issue with the large (out-of-state) vendors was more complicated - it partly dealt with how much of their total sales volume could be attributed to, and taxed by, PA.