Small business interest rates could rise to 24% or higher by 1985, William Barth, managing partner for small business practice at Arthur Andersen & Co., testified in Congress recently. Many small-business owners are increasingly irked because congressmen and lobbyists are more concerned about taxes than about interest rates. "I don't give a damn about taxes when I can't afford the cost of money," complained one participant in a Small Business United lobbying program. He has the sympathies of Rep. Byron Dorgan (D-N.Dak.), who comments, "Capital formation tax breaks are useful only if the company has access to capital." Dorgan has proposed a resolution to insure that 48% of all business taxcut benefits flow to small business, which is responsible for 48% of private sector Gross National Product.