WASHINGTON -- Mailing a letter costs a little more, with the price of a first-class stamp rising to 42 cents Monday.

People who planned ahead and bought Forever stamps for 41 cents each can still use them without extra postage.

Forever stamps also are going up to 42 cents. However, buyers may want to stock up anyway, looking ahead to next May when prices are expected to be adjusted again.

The cost to mail a post card also goes up a penny, to 27 cents. Certified mail costs a nickel more, at $2.70.

Priority and express mail also are getting more expensive.

Under the Postal Accountability and Enhancement Act, mailing prices will be adjusted annually each May, according to the U.S. Postal Service. Customers will be notified 90 days before the price changes each year.