The IRS instructions do not specify how many homes or properties you may include when deducting real estate taxes on Schedule A (Form 1040) Itemized Deductions. The only limitation appears to be that you cannot deduct on Schedule A the real estate taxes you paid for a property used for business. The taxes for business property would need to be deducted on the appropriate business form, if applicable.

Per IRS Instructions for Schedule A, page A-7:

Line 5b

State and Local Real Estate Taxes

Enter on line 5b the state and local taxes you paid on real estate you own that wasn't used for business, but only if the taxes are assessed uniformly at a like rate on all real property throughout the community, and the proceeds are used for general community or governmental purposes. Pub. 530 explains the deductions homeowners can take.

To enter your deductible real estate taxes into the TaxAct program:

1. From within your TaxAct return (Online or Desktop), click Federal (on smaller devices, click in the top left corner of your screen, then click Federal).
2. Click the Itemized or Standard Deductions dropdown, then click Taxes paid.
3. Continue with the interview process until you reach the screen titled Enter any other deductible taxes paid in 2021, click the data entry field below Type of tax, and type "Real Estate Taxes Paid", and then enter the Amount paid.

Note that any link in the information above is updated each year automatically and will take you to the most recent version of the webpage or document at the time it is accessed.