Postage rates are increasing on Monday, May 11 for first class postage and other services. .. it's not too late to lock in the current rate by buying Forever Stamps. "If you buy them today at today's price, it doesn't matter if you use them in numerous years to come, even 100 years from now, that stamp will still be good as a first class stamp, even though you paid 42 cents for it," But time is of the essence, because the Forever Stamp rate also will increase on Monday.