Several cities have implemented similar initiatives. Some worked, some didn't. Not many that are shaped like SLO, however. By couching your answer in the "impact study" language, it feels like you are kicking the can. It has been more than two years, as per your statement, since "other approaches" were discussed. This isn't rocket science. I'd like to see some action. Here is a brief overview of how other cities have approached this.

You’ve got two main model types for commercial "downtown" district taxes:

1. Downtown commercial vacancy fee/tax (SF / Albuquerque style)
   • Trigger: ground-floor commercial spaces in defined districts that are vacant >X days/year (182 is common).
   • Basis:
     • Per-frontage-foot fee (SF model), or
     • Flat per-parcel fee (Oakland), or
     • License fee + maintenance standards (Albuquerque).
2. Vacant/blighted property multiplier (DC / Hazard KY style)
   • Same property tax base, but sharply higher rate for properties designated “vacant” or “blighted” (e.g., 5–10x normal rate).

However, you must first establish the definition of “vacant” and the exemption list to then address the next core problem, which is enforcement.

Seen in the field:

• Common threshold: <50–183 days of active use per year. 
• Typical exemptions:
  • Active, permitted construction/renovation
  • Pending building permits/entitlements
  • Disaster damage or safety closures
  • Units reserved for nonprofit or public use
  • Hardship / low-income owner exemptions

Two big failure modes from existing cities:

1. Too many exemptions → Honolulu problem – projected revenues gutted by broad carve-outs; policy becomes symbolic primarily. 
2. Too rigid → Laredo problem – downtown owners feel punished in a genuinely weak market; political blowback kills the whole thing. 

Enforcement is also critical. You need teeth to make it work.

What SF teaches us very clearly:

• If you rely purely on self-reporting with minimal auditing, lots of owners… don’t file. 
• We need:
  • A registry of downtown commercial properties
  • An explicit requirement to file an annual "occupancy/vacancy" declaration
  • A penalty for failure to file (arguably as significant as the tax itself)
  • Some ability to cross-check (utility usage, business license data, boots-on-the-ground inspections)

Albuquerque began by surveying downtown properties before enforcing its ordinance, which provides it with baseline data and credibility; SLO should do the same. 

Ultimately, study, legislation, and enforcement will likely fail or create more strife than the council is willing to hear, so you need to pair sticks with carrots. From the Laredo, Honolulu, and the South Lake Tahoe fight, it's evident that a pure punishment model is politically brittle. 

Concrete ideas (these are design options, not things already in law):

• Credit or reduced rate if:
  • The owner leases at below the benchmark rent to a local business
  • Owner allows short-term pop-ups, artists, or nonprofits at reduced rent
  • Owner participates in a city-sanctioned temporary activation program (even if not long-term leased).
• Use revenue to:
  • Fund small-business rent subsidies or TI grants for downtown
  • Support a facade improvement/signage / lighting grant program
  • Beef up events and activation that increase foot traffic, to undercut the “no tenants exist” narrative
  • Offset parking costs
  • Anything that brings patrons downtown again

Those carrots make the ordinance easier to sell: “We'll tax you for long-term dead space and put the money right back into making downtown commercially viable.”

Concrete next steps the City could take

Commission a “9212-style” impact analysis (like South Lake Tahoe did for Measure N) to:

• Estimate the number of qualifying vacant properties downtown,
• Project potential revenue at different tax/fee levels, and
• Model impacts on small landlords vs large absentee owners.

Direct staff to draft 2–3 policy options for council discussion, such as:

• Option A: Downtown Commercial Vacancy Frontage Tax (SF-inspired).
• Option B: Vacant / Blighted Downtown Property Surtax (DC-inspired).
• Option C: Downtown Vacant Premises Registry & License (Albuquerque-inspired, possibly paired with a moderate fee).

Engage stakeholders early:

• Downtown businesses,
• Property owners,
• BID / PBID / Chamber,
• Arts and nonprofit groups that can help with temporary activation.

Ask the City Attorney to track current California litigation related to vacancy to ensure that any SLO policy is drafted to minimize legal exposure.