For some time now, the CDTFA has been reaching out to people like Freifelder who sell into the state through the Amazon marketplace. It knows who to contact because Amazon was required to share third-party seller information with the department last fall, as it’s had to do with several states.
California knows these marketplace sellers have or had inventory stored for sale in the state, which gives them physical nexus and an obligation to collect and remit sales tax. Presumably, the CDTFA is only contacting businesses that aren’t registered or collecting tax as the state thinks they should.
When this first came to the attention of Fiona Ma, Treasurer of the State of California, she urged Governor Gavin Newsom to “direct CDTFA to cease this activity”; Ma takes the position that marketplace facilitators, not marketplace sellers, should be responsible for sales tax.
The governor must not have done as Ma asked, because out-of-state marketplace sellers with inventory in the state are still receiving letters from the CDTFA. However, Gov. Newsom did sign a bill into law that holds marketplace facilitators liable for the tax due on all sales made through the marketplace. It took effect October 1, 2019.
Because of California’s new law, Amazon is now required to collect the tax due on Brian Freifelder’s Amazon marketplace sales in California. But it wasn’t responsible for that tax prior to October 1.
According to the CDTFA’s Tax Guide for Marketplace Facilitator Act, if you have a physical presence in the state (“inventory”), “you are engaged in business in California.” For out-of-state businesses, physical presence includes having inventory "stored in a third-party fulfillment center in California.”