You can view San Francisco property tax bills online but keep in mind that because of said Prop 13, discussed below, assessed value bears no relationship to market value.
Similarly, from the Assessor's site, with parcel numbers in hand you can view current Marin County tax bills.
Under Proposition 13 the County tax rate is 1%. Any rate greater than the 1% is comprised of voter-approved overrides.
For the current tax rate in San Francisco, itemized to include overrides, as well as prior years back to 1987, see
the history of property tax rates.
In Marin County, identifying online the tax rate for a given parcel is very tedious. There are tax rate area books maintained by the Auditor Controller. This is the 2005-2006 book. So, one would have to first have the parcel number, and from there the tax rate area. A call to the Marin Assessor's office might save some time: (415) 499-7215.
Under Proposition 60 individuals over 55 may be able to transfer their property tax basis to a replacement home of equal or lesser value [possibly up to 110% of the value of the former residence] within the same County. But legal advise is recommended as a County Assessor need not assume that the "sale price" of the former or of the replacement home is "market value".
This is the
San Francisco Assessor's Claim for Transfer of Base Year Value information page.
This is the Marin County Assessor's Claim for Transfer of Base Year Value information page.
I am advised that there is no price cap on Prop 60 transfers. It applies whether the current home is worth $800,000 or $8,000,000. Once again, Contact the Assessor's Office for current details.
Under Proposition 90, the benefits available under Prop 60 may be honored in a County other than the County in which the taxpayer's home was located, ONLY IF that County has agreed to participate in the Prop 90 program. See Prop 90 update provided by the California Association of Realtors, listing which Counties have opted in, and which have opted out.