The U.S. Postal Service filed Monday notice with regulators to raise prices on its Priority Mail service by 3.5%, and for its Priority Mail Express service by 1.2%, starting Jan. 24. If approved by the Postal Regulatory Commission, the "new domestic competitive prices" will increase to $8.45 from $8.30 for a small-flat rate box, to $15.50 from $15.05 for a medium flat-rate box and to $21.90 from $21.10 for a large flat-rate box. In additions, prices would rise to $7.95 from $7.75 for regular flat-rate envelopes, to $8.25 from $8.05 for legal flat-rate envelopes and to $8.55 from $8.40 for padded flat-rate envelopes. "Although Mailing Services price increases are based on the consumer price index, Shipping Services prices are primarily adjusted according to market conditions," the USPS said in a statement. "The Governors believe these new rates will keep the Postal Service competitive while providing the agency with needed revenue." The USPS noted that "unlike some other shippers," the Postal Service does not add surcharges for fuel, residential delivery or regular Saturday delivery.