(750 ILCS 5/610) (from Ch. 40, par. 610)
Sec. 610. Modification.
(a) Unless by stipulation of the parties or except as provided in subsection (a‑5), no motion
to modify a custody judgment may be made earlier than 2 years after its
date, unless the court permits it to be made on the basis of affidavits
that there is reason to believe the child's present environment may endanger
seriously his physical, mental, moral or emotional health.
(a‑5) A motion to modify a custody judgment may be made at any time by a party who has been informed of the existence of facts requiring notice to be given under Section 609.5.
(b) The court shall not modify a prior custody judgment unless it finds by
clear and convincing evidence, upon the basis of facts that have arisen since
the prior judgment or that were unknown to the court at the time of entry of
the prior judgment, that a change has occurred in the circumstances of the
child or his custodian, or in the case of a joint custody arrangement that a
change has occurred in the circumstances of the child or either or both parties
having custody, and that the modification is necessary to serve the best
interest of the child. The existence of facts requiring notice to be given under Section 609.5 of this Act shall be considered a change in circumstance. In the case of joint custody, if the parties agree to a
termination of a joint custody arrangement, the court shall so terminate the
joint custody and make any modification which is in the child's best interest.
The court shall state in its decision specific findings of fact in support of
its modification or termination of joint custody if either parent opposes the
modification or termination.
(c) Attorney fees and costs shall be assessed against a party seeking
modification if the court finds that the modification action is vexatious
and constitutes harassment.
(d) Notice under this Section shall be given as provided in
subsections (c) and (d) of Section 601.
(Source: P.A. 94‑643, eff. 1‑1‑06.)