To notify the IRS of an address change, you can use Form 8822, Change of Address [1].
You can:
Download Form 8822 from www.irs.gov
Order it by calling 800-TAX-FORM (800-829-3676)
Note that while the IRS will automatically update your address when you file your next tax return, it's important to file Form 8822 to ensure you receive any notices in the meantime.
The U.S. Postal Service does not forward certain types of federal and certified IRS mail [1].