California Starts Taxing SaaS in 72 Days. The Rules Are Still in Draft.

For more than three decades, California left most software sold as a service out of its sales tax base. That ends in 72 days. On January 1, the state that hosts much of the U.S. software industry will start taxing the subscriptions that industry sells, at combined rates above 10% in some of its largest cities. The law itself has been on the books since June. What finance teams still do not have is final rules, and the contracts, renewals and 2027 budgets that the tax will hit are being set now.

A $2 Billion Base Expansion With a January 1 Start

Governor Gavin Newsom signed SB 122 on June 29 as a trailer bill to the 2026-27 budget. According to BDO's analysis of the law, it applies sales and use tax to digital prewritten software "regardless of how it is delivered," whether on physical media, by download or by remote access, and the state estimates the change at roughly $900 million a year for the general fund and $1.1 billion in local sales tax revenue. Custom software written to a single customer's special order stays exempt, as do services that primarily involve human effort, though BDO notes that exemption does not reach the SaaS itself.

The carve-outs are narrower than many software companies assumed. RSM's tax alert lists the exclusions as digital assets, music, streaming video, e-books, video games, digital artwork and certain cloud infrastructure services that let customers run their own software. Everything else in a typical business software stack is in scope. RSM puts the full budget package at about $1.4 billion in additional revenue in fiscal 2027, driven mainly by the broader sales tax base.

The rate a customer pays depends on where it sits. A compliance update from Sales Tax People sets the statewide rate at 7.25%, with combined rates of 8.625% in San Francisco, 10.25% or more in Los Angeles and 11.25% in Santa Monica. It also points out the nexus effect: SaaS revenue that used to be nontaxable now counts toward California's $500,000 sales threshold, so a seller with $600,000 of California subscription revenue and no prior registration has nexus on January 1.

The Draft Rules Decide Which Renewals Get Taxed

The statute leaves most of the operational detail to the California Department of Tax and Fee Administration. The CDTFA published a discussion paper with draft emergency regulations on September 1 and held an interested parties meeting on September 10. Snell & Wilmer's review of the draft reports that practitioners and business groups at that meeting warned it diverges from other states and could impose extraordinary burdens.

The transition rules are the part with a deadline attached. Under the draft, a sale occurs when the right to use the product transfers, regardless of when it is paid for. A one-time license paid in December 2026 with access starting January 1 is taxable. Access that starts in December and is paid in January is not. A monthly subscription that starts in December with a 12-month commitment is taxed only for billing periods on or after January 1. In other words, prepaying a renewal before year-end does not avoid the tax unless access actually begins in 2026.

Sourcing is the second surprise. The draft sends a sale to the purchaser's known California address in this order: billing, then shipping or delivery, then the payment instrument's address, then the most recent mailing address. If no California address applies, the sale is treated as outside the state. Leading with the billing address is unusual, and for a company billed at a headquarters outside California while its staff use the software inside it, the answer flips. Separately, a product bought outside the state and used in California within 90 days is presumed to be for California use.

For multi-state buyers, the draft lets a purchaser apportion tax with a multiple points of use certificate, using "any reasonable method that is consistent and uniform." Allocation by number of users or computers is presumptively reasonable, while allocation by server location is not. The draft also treats a generalized AI tool sold to many customers as taxable prewritten software, even when it is tuned for a single jurisdiction.

Big Buyers Inherit the Filing Burden

The law shifts work onto the largest customers. When a buyer's purchases of digital products from one seller exceed $5 million in a calendar year, the seller is relieved of collecting the tax and the buyer must self-assess use tax and hold a direct payment permit. For 2027 the test uses the current year's spend, and from 2028 the current or preceding year. A buyer can request a waiver, but under the draft it must do so before the purchase it covers.

None of this is final. KBF Advisory's timeline shows written comments closed September 24, with the CDTFA expected to post its notice and submit the package to the Office of Administrative Law around December. Permanent rulemaking is expected by mid-2027. That leaves finance teams configuring tax engines and signing renewals against rules that could still change in the final weeks before they take effect.

Investors have noticed the opportunity in that complexity. CFO Dive reported on October 15 that Numeral, an AI-assisted sales tax compliance company that charges $75 per return filed, raised about $100 million in a Series C round. Its vice president of finance, Hudson Bova, said investors want to make sure a company's definition of annual recurring revenue lines up with theirs, a point that matters for California sellers deciding whether newly collected tax will sit inside or outside reported ARR.

The Playbook for the Next 72 Days

• Classify every product line: Map each SKU to taxable prewritten software, exempt custom software, human-effort services or excluded digital infrastructure, and document the reasoning for anything near the IaaS and PaaS line.
• Audit renewal start dates, not invoice dates: List every California contract with access beginning on or after January 1 and confirm the billing system taxes the 2027 periods, including multi-year deals priced before the law passed.
• Fix customer address data: Because the draft sources to the billing address first, clean billing, shipping and payment addresses now so the tax engine can apply the right local rate.
• Re-test California nexus: Add SaaS revenue to the $500,000 threshold calculation and register before January 1 if the new base pushes the company over the line.
• Model the $5 million buyer rule from both sides: Sellers need to know which customers will cross it, and large buyers need a direct payment permit and a use tax process in place before the first January invoice.
• Rebuild the 2027 software budget: Buyers with California users should add the local combined rate to subscription lines now, while 2027 budgets are still open.