What Counts as a Substantial Change in Circumstances for Child Support in South Carolina
In South Carolina, a family court modifies child support on a substantial change in circumstances. The agency treats a new amount 20% lower as substantial, and only payments accruing after the modification can change.
What is a substantial change in circumstances for child support in South Carolina?
The statutes we read do not define it. Where a request goes through the state child support division, it may object if the request does not show “changed circumstances as provided by law”, and then advises the parent that a petition for review may be filed with the Family Court (S.C. Code 63-17-830(A)). The family court may make orders about the maintenance of children from time to time after final judgment, as the circumstances and the nature of the case make fit, equitable and just (20-3-160).
Is there a percentage rule?
Not in the statutes we read. The state child support agency treats a change as substantial when the new amount is 20% less than the old, according to instructions in a court self-help packet (packet); that is a reference, not a rule. Law-firm sources quote other figures such as 15%, so treat any percentage as a guide. The South Carolina child support modification calculator shows your gap against the 20% reference.
| Existing monthly order | Guideline at or above | or at or below |
|---|---|---|
| $200 | $240 | $160 |
| $500 | $600 | $400 |
| $800 | $960 | $640 |
| $1,500 | $1,800 | $1,200 |
With an $800 order, $1,000 is 25% higher and reaches the reference; $900 does not.
What if the other parent has moved out of state?
The family court keeps continuing, exclusive jurisdiction to modify its order in the situations the interstate sections set out (63-17-3050), so check where the order was made before you file elsewhere.
Who may start a case?
Any interested person may petition the court to order persons legally chargeable to provide support (63-17-340), and either party to the original action can ask to move the case to the family court of the other party’s county (63-17-320).
Why does South Carolina require a showing?
The court wants a change since the last order, not a reargument. Bring pay records before and after, custody calendars if parenting time changed, and bills for any new child expense. A gap alone, without a change, may not be enough.
What if the other parent also asks for a change?
Either party may file; the court can change the amount in either direction, so a request to lower support can lead to a recalculation that raises it. Bring complete income records either way.
Do new South Carolina guidelines count?
Practitioner commentary says applying revised guidelines alone does not automatically count as a change for existing orders, except in cases handled by the state agency; we did not verify the rule in the statutes. Ask a licensed South Carolina attorney whether the revised guidelines help your case.
From what date can the order change?
Only payments accruing after the modification may be modified (63-17-830(C)), and practitioner commentary says the new amount runs from the date the petition was filed. Every month before filing is lost:
| Monthly difference | Lost after 6 months | Lost after 12 months |
|---|---|---|
| $100 a month | $600 | $1,200 |
| $200 a month | $1,200 | $2,400 |
| $400 a month | $2,400 | $4,800 |
Federal law also bars retroactive modification of support already due (42 U.S.C. 666(a)(9)).
What happens next?
Read how to modify child support in South Carolina for the filing steps, and check what stays owed with the South Carolina arrears calculator.
Frequently asked questions
What is a substantial change in South Carolina child support?
A change in circumstances since the order, shown to the family court; the statutes do not give a percentage.
Does a 20% gap guarantee a South Carolina modification?
No. It is the agency's reference line, not a rule.
Do revised South Carolina guidelines modify my order by themselves?
Practitioner commentary says not by themselves except in state-agency cases; ask a licensed attorney.
Can South Carolina modify support that already accrued?
No. Only payments accruing after the modification may be modified.
Where do I start a South Carolina reduction?
With a Support Reduction Complaint (SCCA451) or a request to the Child Support Services division.
Official sources
- S.C. Code 63-17-830: modification of orders
- S.C. Code 20-3-160: maintenance of children
- S.C. Code 63-3-530: family court jurisdiction
- Court self-help packet: 20% reference
- South Carolina Judicial Department: family court FAQ
- 42 U.S.C. 666(a)(9): no retroactive modification of support already due
A local family law attorney can review your situation — many offer a free consultation.
This is general information, not legal advice. It is based on the cited South Carolina statutes, rules and court opinions, and every case turns on its own facts. Confirm how the law applies to your situation with a licensed South Carolina attorney.