San Francisco STR OSTR Enforcement Defense

The situation

Alex, 41, has been renting out a spare bedroom in her SF apartment as a hosted Airbnb since 2021. She registered with OSTR in 2022 and renewed in 2023, but missed the 2024 renewal deadline because Airbnb stopped reminding hosts about annual OSTR renewals. In January 2026, SF's new automated monitoring system (cross-referencing Airbnb listings with OSTR's database under SB 346) flagged her listing as unregistered. She received a Notice of Violation: "Operating Short-Term Rental Without Valid Registration, $484/day from January 10, 2026." She has 15 days to respond.

(a) Her situation is salvageable, a lapsed registration is different from never having registered. Alex registered in 2022 and renewed in 2023. The 2024 lapse was an administrative oversight, not intentional operation without registration. OSTR distinguishes between hosts who deliberately operated without registration and hosts whose registrations lapsed. Alex can document her prior registration history, show she applied to renew immediately upon receiving the NOV, and argue for waiver of the per-day penalty accrued during the renewal gap.

(b) Hosted stays (where the host is present) are treated differently from un-hosted stays. Alex hosts as a hosted rental, she's present in her apartment during guest stays (using the spare bedroom only). Hosted stays are NOT subject to the 90-day annual cap. OSTR's enforcement data suggests some hosts receive NOVs that incorrectly count their hosted nights toward the 90-day un-hosted cap, this is an OSTR classification error that can be contested.

(c) The fine is accruing at $484/day. From January 10 through January 25 (15 days) = $7,260 already. Every day Alex doesn't respond adds another $484. An immediate NOV response can stop the accrual and preserve her right to contest the penalty amount.

Who receives this

San Francisco Airbnb/VRBO hosts who have received OSTR Notices of Violation. Primary audiences: (1) SF hosts with lapsed registrations discovered by the 2026 SB 346 automated monitoring system; (2) SF hosted-rental hosts whose nights were incorrectly classified as un-hosted by OSTR; (3) SF hosts who unknowingly exceeded the 90-day un-hosted cap and need to document their calendar-day calculation dispute.

Why the agency will not advise you

OSTR cannot advise violating hosts on how to contest its own NOVs. The $484/day fine creates immediate financial urgency. SB 346 (2026) and automated monitoring create a new enforcement wave, hosts who were previously undetected are now being identified systematically.

Key facts, with sources

• The San Francisco Office of Short-Term Rentals (OSTR) enforces SF Admin Code § 41A. Under SF's STR ordinance, hosts must: (1) register with OSTR annually ($250/year); (2) maintain San Francisco as their primary residence (defined as residing in SF for 275 or more days per year); (3) obtain a Certificate of Primary Residency from the SF Assessor-Recorder's office; (4) for un-hosted stays: not exceed 90 days per calendar year total across all STR platforms. Violations trigger a Notice of Violation (NOV) from OSTR with a 15-day response window. Penalties: $484/day for first violations, $968/day for repeat violations. Hosts can also be added to the OSTR 'Ineligible Host List,' which platforms are required to honor by removing the host from their marketplace. Approximately 4,000–8,000 SF STR hosts are registered; an estimated 2,000–5,000 additional active unregistered listings are operating without registration. Source: San Francisco Short-Term Rental Laws 2026: A Complete Guide — JakenFinanceGroup · Complaints and Enforcement — SF Planning · San Francisco Short-Term Rental Regulations 2025 — Guestable
• California Senate Bill 346 (effective January 1, 2026) gives California cities, including San Francisco, the legal authority to compel Airbnb, VRBO, and other short-term rental platforms to share data about STR listings operating within the city. Previously, platforms had resisted sharing host data with local regulators; SB 346 removes that barrier. San Francisco is also developing an automated monitoring system (2026) that cross-references platform listings with OSTR's official registered host database in real-time, flagging non-compliant properties within 24 hours of listing. These two 2026 changes dramatically expand OSTR's enforcement reach and are expected to significantly increase the number of NOVs issued to previously undetected unregistered hosts. Source: New State Law Helps Cities Get Short-Term Rental Information from Airbnb, VRBO — Best Best & Krieger · Airbnb & Short-Term Rental Laws in San Francisco — 2026 — Steadily

When to bring in a professional

Self-serve responses fit routine cases: clear facts, amounts a business can absorb, and a deadline still ahead of you. Bring in a licensed professional when the amount at stake is large relative to their fee, the facts are genuinely disputed, criminal exposure is possible, or the deadline has already passed. A short paid consultation to sanity-check your plan is often worth it even when you handle the filing yourself.

All sources for this guide

1. San Francisco Short-Term Rental Laws 2026: A Complete Guide — JakenFinanceGroup
2. Complaints and Enforcement — SF Planning
3. San Francisco Short-Term Rental Regulations 2025 — Guestable
4. New State Law Helps Cities Get Short-Term Rental Information from Airbnb, VRBO — Best Best & Krieger
5. Airbnb & Short-Term Rental Laws in San Francisco — 2026 — Steadily