You can edit your tax return up until the time you e-file it. After you e-file, you cannot change it. So wait to enter the property tax if you expect it to affect your tax due or refund. Your data will be auto-saved in online TT until you come back to enter more information.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**