Moving can be a difficult experience so it is easy to forget to file that very important Change of Address form with the Post Office.
Just think of all the important mail you could miss if you don't tell the mailman that you have moved.
You won't get important Medicare or Medicaid information.
Your Social Security or other benefit checks won't get to you.
If the Internal Revenue Service sends your tax refund to your old address, it won't get to you.