No matter how many times Congress "reforms" the federal tax system, it keeps going back and tinkering some more - usually trying to give one group or another a special tax break.

This Congress is no different. Despite the massive tax reform of 1986 to reduce deductions and tax brackets, and to simplify the system - which it only succeeded in making more complicated - more changes are in the works.Some of the proposals make sense, such as repealing the requirement that farmers pay federal tax on diesel fuel for farm equipment, and then apply for a rebate at the end of the year. If farmers are exempt from the tax, why go through this dance of paying and rebating?

However, the trouble with any tax measure, even one as simple as the diesel fuel tax for farmers, is that it becomes a vehicle for many other tax proposals to hitch a ride.

Other suggestions call for extending one or two years some tax breaks that have expired or are due to expire this year. These include a tax exemption for revenue bonds that help first-time home owners; a credit for increased research and development; a tax credit that encourages employers to hire the poor.

Various groups want to reduce the tax on capital gains, give tax breaks to encourage parents to save for their children's education, and to impose a new tax on single-premium life insurance policies, under which upper-income investors buy large policies against which they can then borrow tax-free.

Given the horribly complicated tax system, there probably are always going to be things that need to be fixed or improved, but it would be nice if Congress stopped tinkering for a year or two until the country and its tax experts can figure out just what the tax laws are.