The Mississippi Supreme Court held that the taxpayer bears the burden to prove that an alternative apportionment method imposed by the State is arbitrary and unreasonable. Rejecting the taxpayer’s original cost-of-performance filing position, the Department of Revenue applied an alternative apportionment method utilizing market-based sourcing. On appeal, the Chancery Court found the Department’s “application of equitable apportionment and the market-based sourcing method to be somewhat troubling,” but upheld the alternative apportionment method because it did not “rise to the level of arbitrary or unreasonable.” The Court of Appeals reversed and held that the party invoking alternative apportionment bears the burden of showing that: (1) the standard apportionment method does not fairly represent the extent of the taxpayer’s business activity in the state; and (2) the alternative method is reasonable. See Microsoft Corp. v. Franchise Tax Bd., 39 Cal.4th 750 (Cal. 2006). Unfortunately, the Mississippi Supreme Court reversed the well-reasoned Court of Appeals decision, ignoring substantial case law interpreting the burden related to an alternative apportionment adjustment. It instead relied on Mississippi’s Administrative Procedures Act, which places the burden of proof on taxpayers seeking refunds in Chancery Court. Therefore, Mississippi taxpayers now shoulder the burden to prove that the Department’s alternative apportionment method is improper. Equifax, Inc. v. Mississippi Dep’t of Revenue, — So.3d — (Miss. June 20, 2013).