WASHINGTON – The cost of mailing a letter will go up on May 14, but you’ll be able to lock in that price – no matter how rates rise in the future – by buying the new “forever” stamp.

The post office governing board agreed yesterday to accept the new 41-cent rate for first class mail recommended in February by the independent Postal Regulatory Commission.

The board also agreed to the proposal for a “forever stamp,” that will always be valid for mailing a letter no matter how much rates increase.

James C. Miller III, chairman of the postal board, said the forever stamp could go on sale as soon as next month, at the 41-cent rate.

The postal governors asked the regulatory commission to reconsider some of its proposals, saying the suggested price for sending things like catalogs was too high.

For most people, the first-class rate has the greatest impact and the cost of sending a letter will rise from 39 cents to 41 cents, a penny less than the Postal Service had originally requested.

But folks sending heavier letters – such as wedding invitations – will see a reduction in the price.

That’s because the 41-cent rate is for the first ounce, but each additional ounce will cost just 17 cents, down from the current 24 cents.

That means a two-ounce letter will cost 58 cents to mail, compared with 63 cents now.

Also expected to be attractive to many people is the forever stamp.

The first forever stamps will sell for 41 cents apiece, but they won’t have a price printed on them and they will remain valid for sending a letter regardless of any future rate increases.

While a forever stamp will always be valid for mailing a latter, that doesn’t mean the price won’t go up. If rates were to increase to 45 cents, for example, that’s what a forever stamp would sell for.

But stamps already purchased at a lower rate could still be used without adding extra postage.

Miller said in a telephone interview that there is no limit on sales of the forever stamps but noted they are generally intended for consumers and won’t be produced in the massive rolls often used by businesses.