Proposition 13 limits the taxation of property to 1.2% of a propertyâ€™s assessed value (as a Buyer this is the sales price), plus special assessments and improvement bonds approved by the voters. Property tax increases are limited to a 2% increase in the assessed value of the property per year.
If you are looking at other costs, such as Hazard Insurance, you can estimate this at .35% of loan amount per year.
As David points out, the County online system is good for checking taxes that are due.
Current property taxes show up on the property profile in the MLS - Your Realtor can help you with this.
You may also be able to access property tax information through the County's Website: