At any time after final judgment, and child custody or support order may be changed:

“In any action for divorce from the bonds of matrimony the court may at any stage of the cause, or from time to time after final judgment, make such orders touching the care, custody and maintenance of the children of the marriage and what, if any, security shall be given for the same as from the circumstances of the parties and the nature of the case and the best spiritual as well as other interests of the children may be fit, equitable and just.”   S.C. Ann. Code §20-3-160

In particular, “this authority includes the right to modify any such decree, judgment, or order for child support as the court considers necessary upon a showing of changed circumstances. No such modification is effective as to any installment accruing prior to filing and service of the action for modification. Additionally, the family court has the right to hold any arrearage in child support in abeyance.” S.C. Ann. Code §63-17-310  “The court shall consider the following factors which…may be used in determining whether a change in circumstances has occurred which would require a modification of an existing order:

(1) educational expenses for the child or children or the spouse, to include those incurred for private, parochial, or trade schools, other secondary schools, or post-secondary education where there is tuition or related costs;

(2) equitable distribution of property;

(3) consumer debts;

(4) families with more than six children;

(5) unreimbursed extraordinary medical or dental expenses for the noncustodial or custodial parent;

(6) mandatory deduction of retirement pensions and union fees;

(7) support obligations for other dependents living with the noncustodial parent or noncourt ordered child support from another relationship;

(8) child-related unreimbursed extraordinary medical expenses;

(9) monthly fixed payments imposed by a court or operation of law;

(10) significant available income of the child or children;

(11) substantial disparity of income in which the noncustodial parent’s income is significantly less than the custodial parent’s income, thus making it financially impracticable to pay what the guidelines indicate the noncustodial parent should pay;

(12) alimony; because of their unique nature, lump sum, rehabilitative, reimbursement, or any other alimony that the court may award, may be considered by the court as a possible reason for deviation from these guidelines;

(13) agreements reached between parties; the court may deviate from the guidelines based on an agreement between the parties if both parties are represented by counsel or if, upon a thorough examination of any party not represented by counsel, the court determines the party fully understands the agreement as to child support. The court still has the discretion and the independent duty to determine if the amount is reasonable and in the best interest of the child or children.”

S.C. Ann. Code §63-17-470