Interesting to note that apparently (after Westlaw searches for the term) Minnesota courts have not issued a tax opinion either accepting or rejecting equitable recoupment, the federal tax principle under which the taxpayer may raise time-barrred refund/credit claims to offset tax assessments based on the same transaction, e.g. Estate of Orenstein v. Commissioner, T.C.Memo. 2000-150 (taxpayer allowed to use time-barred estate tax refund claim to offset income tax imposed on the same transaction). Many states have explicitly adopted equitable recoupment, including neighboring Wisconsin, American Motors Corp. v. Wisconsin Department of Revenue, 219 N.W.2d 300 (Wis. 1974). And many states, like Wisconsin, allow a broad definition of the required ‘same transaction’, allowing barred refund claims to offset tax assessments that all are with respect to the same period, whether or not there is a common factual transaction.
But apparently in Minnesota the issue has never been litigated. Given that Minnesota also lacks the equivalent of the federal mitigation statutes – I.R.C. §1311 et seq., another relief for time-barred claims, the issue should be litigated.