Wyo. Stat. § 15-6-402
If the contract or contracts for any improvements have been awarded, or the city or town has determined to construct the improvements by the use of its own equipment, labor and materials, or any of them, or avail itself of any state or federal program contributing to the cost of the improvement, the city engineer, either immediately, or at the council's discretion upon the completion of the improvements, shall levy an assessment upon the property included in the district. The assessment shall include as a part of the cost the contract price, or the estimated costs of construction, together with the expense of engineering, inspection, advertising, levying and collecting assessments and all other charges which the city or town may have incurred or expects to incur in making and financing the improvements, or the portion of the costs designated by the governing body to be defrayed by special assessments.
W.S. 15-6-402