(1) As used in this section, "custody" means sole or joint custody, whether ordered by a court or agreed to by the parties.
(2) No motion to modify a custody decree shall be made earlier than two (2) years after its date, unless the court permits it to be made on the basis of affidavits that there is reason to believe that:
(a) The child's present environment may endanger seriously his physical, mental, moral, or emotional health; or (b) The custodian appointed under the prior decree has placed the child with a de facto custodian.
(3) If a court of this state has jurisdiction pursuant to the Uniform Child Custody Jurisdiction Act, the court shall not modify a prior custody decree unless after hearing it finds, upon the basis of facts that have arisen since the prior decree or that were unknown to the court at the time of entry of the prior decree, that a change has occurred in the circumstances of the child or his custodian, and that the modification is necessary to serve the best interests of the child. When determining if a change has occurred and whether a modification of custody is in the best interests of the child, the court shall consider the following:
(a) Whether the custodian agrees to the modification;
(b) Whether the child has been integrated into the family of the petitioner with consent of the custodian;
(c) The factors set forth in KRS 403.270(2) to determine the best interests of the child;
(d) Whether the child's present environment endangers seriously his physical, mental, moral, or emotional health;
(e) Whether the harm likely to be caused by a change of environment is outweighed by its advantages to him; and (f) Whether the custodian has placed the child with a de facto custodian.
(4) In determining whether a child's present environment may endanger seriously his physical, mental, moral, or emotional health, the court shall consider all relevant factors, including, but not limited to:
(a) The interaction and interrelationship of the child with his parent or parents, his de facto custodian, his siblings, and any other person who may significantly affect the child's best interests;
(b) The mental and physical health of all individuals involved;
(c) Repeated or substantial failure, without good cause as specified in KRS 403.240, of either parent to observe visitation, child support, or other provisions of the decree which affect the child, except that modification of custody orders shall not be made solely on the basis of failure to comply with visitation or child support provisions, or on the basis of which parent is more likely to allow visitation or pay child support;
(d) If domestic violence and abuse, as defined in KRS 403.720, is found by the court to exist, the extent to which the domestic violence and abuse has affected the child and the child's relationship to both parents.
(5) Subject to KRS 403.315, if the court orders a modification of a child custody decree, there shall be a presumption, rebuttable by a preponderance of evidence, that it is in the best interest of the child for the parents to have joint custody and share equally in parenting time. If a deviation from equal parenting time is warranted, the court shall construct a parenting time schedule which maximizes the time each parent or de facto custodian has with the child and is consistent with ensuring the child's welfare.
(6) 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.