home office excess real estate tax

In the home office deduction topic TurboTax Home & Business asks about excess real estate taxes.

My real estate tax does not exceed $10K, but the combination of real estate tax and other state and local taxes definitely does.

Do I have “excess real estate tax”?  After completing the itemized deductions, would I determine amount of state and local taxes above $10K and and enter it as excess real estate tax in the home office deduction topic  (Form 8829)?