The cost of mailing a letter could be going up.

The price of a first-class stamp is expected to rise by a penny come January.

The proposed increase to 45 cents is part of a package that would boost the price of a postcard from 29 cents to 32 cents and also raise the cost of sending international letters, standard mail and periodicals, the agency said in a news release.

Under a 2006 law, the Postal Service can raise rates as long as the cumulative increase doesn’t exceed the inflation rate as measured by the Consumer Price Index, which in this case is 2.1 percent, according to the Postal Service.  The proposed increases were filed Monday with the Postal Regulatory Commission, a five-member oversight body. The PRC has 45 days to review them to make sure they don’t violate the inflation cap, USPS spokesman Dave Partenheimer said in a news release.

Assuming the commission gives its OK, the increases would take effect Jan. 22 and would be the first for a first-class stamp since May 2009. The rate changes are expected to generate approximately $888 million in new annual revenue, Partenheimer said.

“The overall average price increase is small and is needed to help address our current financial crisis,” Postmaster General Patrick Donahoe said in a statement. “We continue to take actions within our control to increase revenue in other ways and to aggressively cut costs. To return to sound financial footing, we urgently need enactment of comprehensive, long-term legislation to provide the Postal Service with a more flexible business model.”