The surcharge "will last just long enough to recover the loss," Commission Chairman Ruth Y. Goldway said.
Bulk mail, periodicals and package service rates will rise 6 percent, a decision that drew immediate consternation from the mail industry. Its groups have opposed any price increase beyond the current 1.7 percent rate of inflation, saying charities using mass mailings and bookstores competing with online retailer Amazon would be among those who suffer. Greeting card companies also have criticized the plans.
"This is a counterproductive decision," said Mary G. Berner, president of the Association of Magazine Media. "It will drive more customers away from using the Postal Service and will have ripple effects through our economy — hurting consumers, forcing layoffs and impacting businesses."
Berner said her organization will consider appealing the decision before the U.S. Court of Appeals.
For consumers who have cut back on their use of mail for correspondence, the rate increase may have little impact on their pocketbooks.
"I don't know a whole lot of people who truly, with the exception of packages, really use snail mail anymore," said Kristin Johnson, a Green Bay, Wis., resident who was shopping in downtown Anchorage, Alaska, while visiting relatives and friends. "It's just so rare that I actually mail anything at this point."
The Postal Service is an independent agency that does not depend on tax money for its operations but is subject to congressional control. Under federal law, it can't raise prices more than the rate of inflation without approval from the commission.
The service says it lost $5 billion in the last fiscal year and has been trying to get Congress to pass legislation to help with its financial woes, including an end to Saturday mail delivery and reduced payments on retiree health benefits.
The figures through Sept. 30 were actually an improvement for the agency from a $15.9 billion loss in 2012.
The post office has struggled for years with declining mail volume as a result of growing Internet use and a 2006 congressional requirement that it make annual $5.6 billion payments to cover expected health care costs for future retirees. It has defaulted on three of those payments.
The regulators Tuesday stopped short of making the price increases permanent, saying the Postal Service had conflated losses it suffered as a result of Internet competition with business lost because of the Great Recession. They ordered the agency to develop a plan to phase out the higher rates once the lost revenue is recouped.
It's unclear where that would take rates for first-class postage in 2016. The regular, inflation-adjusted price would have been 47 cents next year. If inflation rates average 2 percent over the next two years, regulators could deem 49 cents an acceptable price going forward.
The Postal Service has only twice lowered the price of a stamp: in the mid-19th century from 3 cents to 2 cents, and again after the end of World War I. In neither case was the higher price the result of a temporary authorization.
The new price of a postcard stamp, raised by a penny to 34 cents in November, also is effective next month.