The last postal rate increase went into effect on May 11th, 2009. The postal service has not announced the next time the rates will change. To guard against future rate increases consider buying forever stamps. These stamps cost the same amount as regular stamps, but can always be used, no matter what the current postage rate. With 6 postage rate hikes in the past 10 years, forever stamps are a smart strategy to save a little money in the future.