Dumb question, but do you escrow your taxes with your housing payment each month, and if so, does your mortgage company pay your taxes for you? If so, they will have a record of it. Log on to their website and look at your escrow history or the escrow analysis they do annually. I would think that if you don't escrow them and pay them directly, that would be a really big check that would be easy to find in your bank records. The changes in the tax code this year limit the total you can deduct in state income and real estate taxes to $10,000. IIRC, you live in CA, so you are probably paying a lot income taxes and the combination of the two will be more than $10,000. Worst case scenario, put what you paid last year and the two will probably add up to over $10,000 and nobody at the IRS will care.