Wyo. Stat. § 20-2-311 (2026)

(a) Any party, or the department of family services in the
case of child support orders being enforced by the department,
may petition for a review and adjustment of any child support
order that was entered more than six (6) months prior to the
petition or which has not been adjusted within six (6) months
from the date of filing of the petition for review and
adjustment. The petition shall allege that, in applying the
presumptive child support established by this article, the
support amount will change by twenty percent (20%) or more per
month from the amount of the existing order. The court shall
require the parents to complete a verified financial statement
on forms approved by the Wyoming supreme court, and shall apply
the presumptive child support set out in this article in
conducting the review and adjustment. If, upon applying the
presumptive child support to the circumstances of the parents or
child at the time of the review, the court finds that the
support amount would change by twenty percent (20%) or more per
month from the amount of the existing order, the court shall
consider there to be a change of circumstances sufficient to
justify the modification of the support order. The provisions
of this section do not preclude a party or assignee from
bringing an action for modification of a support order, based
upon a substantial change of circumstances, at any time. Every
three (3) years, upon the request of either parent or, if there
is a current assignment of support rights in effect, upon the
request of the department, the court, with respect to a support
order being enforced under this article and taking into account
the best interests of the child involved, shall review and, if
appropriate, adjust the order in accordance with the guidelines
established pursuant to this article. Any adjustment under the
three (3) year cycle shall be made without a requirement for a
showing of a change in circumstances. The commencement of aid
under the personal opportunities with employment
responsibilities (POWER) program, medical benefits under Title
XIX of the Social Security Act, supplemental nutrition
assistance program and supplemental security income (SSI) shall
be considered a substantial change of circumstances requiring
modification of child support.

     (b) Notwithstanding any other provision of law, if the
parties fail to agree that the presumptive child support amount
under W.S. 20-2-304 is appropriate, the court may order the
party seeking to deviate from the presumptive child support
amount to pay a reasonable attorney fee and court costs to the
other party unless, after hearing the evidence and considering
the factors contained in W.S. 20-2-307(b), the court deviates
from the presumptive support amount.

     (c) In addition to the petition authorized under
subsection (a) of this section, the court on its own motion, or
the department without petitioning the court, may increase
monthly child support payments to include amounts for arrearages
or may decrease the monthly child support payment in cases of
emergencies or if the arrearages are paid. Any action by the
department to increase monthly child support payments under this
subsection shall allow the obligor a reasonable opportunity to
contest the action in accordance with the Wyoming Administrative
Procedure Act and rules and regulations adopted by the
department.

     (d) An order for child support is not subject to
retroactive modification except:
             (i)    Upon agreement of the parties; or

          (ii) The order may be modified with respect to any
period during which a petition for modification is pending, but
only from the date notice of that petition was served upon the
obligee as provided by the Wyoming Rules of Civil Procedure, if
the obligor or the department is the petitioner, or to the
obligor, if the obligee or the department is the petitioner.