I am renting a Santa Ana commercial property to a master leaseholder who in turn rents out units to various business tenants. Is my receipt of rents during the term of the master lease still considered to be a business? Do I have to get a business license?

As an owner-lessor who retains ownership of the commercial property at the conclusion of the master lease term, you do need to obtain a Santa Ana business license and report the gross receipts (gross rents) derived from the master lease. The leaseholder-lessor who is renting out units of your commercial rental property pursuant to the master leasehold allowing them to do so is also required to obtain their own Santa Ana business license and must report the gross receipts (gross rents) derived from their unit rentals.