Kay Fishburn is trying to do what a long line of presidents and repeated sessions of Congress have not been able to do - retire the United States national debt. It is a $1.3 trillion challenge.
Mrs. Fishburn, working from her home in this Milwaukee suburb, started the Debt Retirement Network. This year the informal network mailed 13,000 letters urging Americans to take part in ''a historic endeavor.'' Her crusade began 18 months ago. ''I was doing my taxes and listening to the wrangling on a radio program about the budget, and I thought, 'Why doesn't someone just say, it's going to have to be up to us?' '' A few months later she wrote a letter published in the Milwaukee Journal and a few other newspapers which asked citizens to begin sending money to the US Treasury to retire the debt.
Congress created the Public Debt Reduction Fund in 1961 to provide a pocket for contributions of the type Mrs. Fishburn is soliciting. Contributions over the years were modest, but totaled $901,000 by 1982. This year the Internal Revenue Service attached to Form 1040 a notice that said voluntary contributions could be made by separate check and enclosed with tax returns. By April 22 the IRS had received 290 donations totaling nearly a quarter-million dollars.
Mrs. Fishburn doesn't know whether she can take credit for the surge. But she believes that paying even the biggest bill begins with the smallest coin. The alternatives are troubling: ''In the next decade we're going to pay a trillion dollars in interest,'' she said.