The Virginia State Corporation Commission gave the Chesapeake & Potomac Telephone Co. permission yesterday to increase its charges for most telephone service in the state by 5.72 percent, an action that will give the utility an added $22.7 million a year in revenues.

According to a phone company spokesman, the approved surcharge will mean an average monthly increase of about 50 cents for residential customers and $1 or more -- depending on the amount of service provided for business customers.

C & P asked the commission last December to grant it a 5.92 percent surcharge effective March 1 because its revenues were $40 million less than authorized by the commission. The commission reduced the surcharge slightly because C&P's federal income taxes recently were reduced from 48 to 46 percent.

The surcharfe, subject to review at a later commission hearing, is expected to generate about $22.7 million in income for C & P, about $300,000 less than would have resulted from the increase sought by the company. Items excluded from the surcharge are local pay telephone calls, directory assistance charges, long distance calls and toll-free WATS line calls.

According to Fred E. Stone, public affairs district manager for C & P's Northern Virginia office, the company has notified customers of the impending surcharge in their monthly bills.