The art of creative financing took a new twist last week when Charles County decided to lend itself money to put a new computer system in county schools.

The county commissioners agreed to make an eight-year loan at 10 percent interest to the Board of Education for a $580,000 computer system that would tie together financial management, student records and teacher training for the county's 26 elementary, middle and high schools. The board plans to buy the equipment over the next five years.

IBM had offered to finance the equipment alone for 10 percent interest, and Citicorp, a financier for other similar governmental loans, agreed to finance the remaining salaries, services and supplies involved with the system for 13 percent, according to School Superintendent John H. Bloom.

But county Finance Director Richard Winkler took out his calculator and figured that by taking the $580,000 out of the county's general fund over the next five years and transferring the money into the school board budget, the county could avoid paying any interest to outside agencies.

Still, that's not to say the county is doing it only for fun: The commissioners decided they would charge 10 percent interest on the loan. This means by the time 1991 rolls around, the general fund will have received the total interest.

It also means, since the county finances the board, that the county will be paying itself the 10 percent interest. But, as Winkler points out, it's not 13 percent, and it's all staying in the family.