The Agriculture Department has told Puerto Rico and 13 states, including Maryland, that they must reduce the number of errors in their food-stamp operations or face penalties totaling $16.5 million. This is the first time USDA has threatened to impose penalties--a move prompted, officials said, by the high number of mistakes being made.

Nationwide, the $11.3 billion program had an error rate of 12.6 percent, but the 13 states exceeded that average, according to the agency. Alaska had the most errors, averaging 21.7 percent or about one application with errors for every five processed. Maryland's error rate was 16.69 percent and the state could be slapped with $580,954 in penalties if it doesn't reduce its error rate to at least 15.98 percent.

An error doesn't always mean food stamps are being paid to someone who doesn't qualify for them, officials said. Often applicants do not understand government forms or do not bring all the information that social workers need to determine their benefits. And sometimes applicants do not get as many stamps as they deserve because of errors.

The states have until Feb. 1 to submit their plans for reducing the number of errors. Those plans must be implemented by April 1 or USDA says it will levy the penalties, probably by withholding funds, a spokesman said.