Add a certain number of days for a date field

I have one field for a permit decision date, and then I have another field for 180 days from that permit date. The permit date field has data entered, but the 180 day field I would like to calculate by adding 180 days. It is a feature class in a file GDB, and both fields are in date format (mm/dd/yyyy).

Example: Permit Field date is 7/1/2009, I would like the 180 days field to be 12/28/2009.

Thank you for your help.