I thought at one time,maybe it is in the past now, you had a one time exemption on the sale of the primary residence.dont know if there was a monetary limit..good luck....
As I recall it wasn't an exemption as such. It granted "empty nesters" a six month window to reinvest sale proceeds in a smaller house (build or buy) with out applying capital gains. I think it was a once in a lifetime deal to allow seniors to trade down to smaller digs.
Most State laws followed the Federal model. Wisconsin did not, if you bought or rebuilt in Wisconsin w/in six months you got a pass. If you bought or rebuilt out of state Wisconsin hit you up for the Capital Gains, and Federal rules did not. I know a guy who fought it all the way to the State Supreme Court and lost.
That was then, it may not be the case today, check with a tax preparer you trust before proceeding.
Regards & best of luck,
GtG