Wyo. Stat. § 37-13-119
The amount of the assessment is due and collectible without demand within thirty (30) days after the final publication of the assessment resolution and if it is not paid within such time it shall commence to bear interest at a rate fixed by the governing body. The published resolution shall specify the date when interest will commence, the rate of interest, and the period of years over which installment payments may be made. If not paid within the thirty (30) days allowed, it will be conclusively presumed that the owner exercises the right to pay the amount due in equal annual installments bearing interest at the rate specified in the resolution and extending over the period of years not exceeding ten (10) specified in the resolution. The first installment shall become due one (1) year from the date when interest commenced and one (1) installment shall become due on the same day of the same month annually thereafter.
W.S. 37-13-119