A chart yesterday showing deadlines for auto inspections in Virginia listed the wrong date for cars with tags expiring next May. The correct deadline for such cars is May, 1983.

Virginia motorists will get a break tomorrow when the state begins a program that requires vehicles to be inspected once a year, instead of twice. Inspections under the new program will cost $7, compared to $8 annually under the old program.

State police concede that motorists at first may have a hard time figuring out when their vehicle should be inspected. State police say they already have received hundreds of phone calls about the yearly inspection program.

Sgt. J.A. Weathersbee, of the state police, said the basic formula for figuring out when to get an inspection is this: If your license plates expire during the last six months of this year, or if you have bought a new vehicle since July 1, 1981, with a 12-month inspection sticker (instead of the old six-month one), have your vehicle inspected according to your current inspection sticker.

In all other cases, Weathersbee said, motorists should have their vehicles inspected in the same month their license plates expire, even if the inspection sticker indicates otherwise.

For example, if your inspection sticker expires in November and your license plates expire in August, the inspection should be done in November. But if the license plates do not expire until February, the vehicle should be inspected in February.

The new law, approved this year by the General Assembly, reflects a nationwide trend toward annual inspections, police Capt. Roy Terry said.

The state police decided to support the proposed change after the department's safety division conducted a study and concluded that switching from a semiannual to an annual inspection program would pose no threat to highway safety.