Now that pretty much everyone who has real property in California has paid their first installment of tax on it, the pain of paying has resuscitated the old tax reassessment fraud business.
It's safe to say that no one who paid the first installment is eager to fork over the next one in December--just in time for the holidays!
And considering the moribund state of the local real estate market, the possibility that one's property has declined in value is a very real one.
If you're interested in lowering your assessment, get in touch with your county's assessor. In some areas the assessors aren't even asking for comps or other data. They're just knocking down the figure.
As an example of how easy it is to apply, the San Francisco Assessor has an online application right here.
No assessor will ask you for information you can't get by yourself, but all sorts of scammers are going around offering to sell people tax reduction services.
The Merc has an article on the subject that mentions a company asking for $179 fee to arrange reductions. That particular offer is legal, though still a waste of your money. (Pay up to pay less?)
But other folks will just take your dough, mine your financial data for nefarious purposes, and do nothing to lower your taxes.
So if you want it done right ( and cheap) . . . do it yourself!