Wyo. Stat. § 39-17-210: Statute of limitations.

(a) The refund form and receipts, as provided for in W.S. 39-17-209(c)(i) are invalid if not submitted to the department within eighteen (18) months following date of purchase.

(b) Each supplier, refiner, terminal operator, importer, exporter, distributor and dealer shall keep and preserve the records relating to the purchase and sale of diesel fuels three (3) years. The department may authorize, by rule, alternate methods of preserving records required under this section.