What Counts as a Substantial Change in Circumstances for Child Support in Colorado
To modify Colorado child support you must show a substantial and continuing change in circumstances. A guideline recalculation that changes the monthly amount by less than 10% is deemed not substantial and continuing, and a missing medical support provision is a separate ground.
What is a substantial and continuing change of circumstances for child support in Colorado?
Colorado child support may be modified only on a showing of changed circumstances that are substantial and continuing, or on the ground that the order does not contain a provision regarding medical support, such as insurance coverage, payment for medical insurance deductibles and copayments, or unreimbursed medical expenses (C.R.S. 14-10-122(1)(a)). The party asking for the change has to prove it.
What is the 10% rule for Colorado child support modification?
Applying the child support guidelines and the schedule of basic child support obligations to the circumstances at the time of filing, a result of less than a ten percent change in the amount of support due per month is deemed not to be a substantial and continuing change (14-10-122(1)(b)). The statute says what is not enough; it does not say a 10% change is automatically enough. The Colorado child support modification calculator measures the 10% against the existing order, and a change of exactly 10% is not “less than ten percent”.
| Existing order | Above the floor if the guideline is | or |
|---|---|---|
| $500 | $550 or more | $450 or less |
| $800 | $880 or more | $720 or less |
| $1,200 | $1,320 or more | $1,080 or less |
| $2,000 | $2,200 or more | $1,800 or less |
With an $800 order, a guideline amount of $1,000 is 25% higher and clears the floor, $880 is exactly 10% and clears it, and $879 does not.
Can I modify with less than a 10% change?
The statute deems it not substantial and continuing, so you would have to rely on another ground, such as a missing medical support provision or a change of physical care. Courts have found that other facts can show a substantial and continuing change in some situations, but do not count on it.
Does a new guideline schedule matter?
The 10% test applies the guidelines to your circumstances at the time you file, so an updated schedule can move the result. Colorado updated the child support guidelines in HB25-1159, including the schedule and the parenting-time credit (signed bill). Run your numbers in the Colorado child support calculator at filing time.
What if there was a change of physical care?
When a court-ordered, voluntary or mutually agreed change of physical care occurs, the existing support is modified or terminated as of the date physical care changed, and a new order can also be entered retroactively to that date. The court cannot go back more than five years before the motion unless that would be substantially inequitable, unjust or inappropriate (14-10-122(5)).
What if the child support age rules changed?
A decree can be modified as a result of a change in the age for the duty of support, but only for installments accruing after the filing of the motion (14-10-122(4)).
What should you gather?
- Pay stubs, tax returns and other proof of each parent’s income now.
- The current order and its worksheet.
- Records of the change: a termination notice, medical records, insurance costs, a parenting-time change.
- A proposed child support worksheet from the Colorado child support calculator.
What happens next?
Read how to modify child support in Colorado for the forms and the filing date, and check what stays owed with the Colorado arrears calculator.
Frequently asked questions
What is the 10% rule for Colorado child support modification?
A guideline recalculation at filing that changes the monthly amount by less than 10% is deemed not a substantial and continuing change.
Is a 10% change automatic grounds to modify support in Colorado?
No. The statute says less than 10% is not enough; you must still show a substantial and continuing change.
What must I show to modify child support in Colorado?
Changed circumstances that are substantial and continuing, or that the order lacks a provision on medical support.
Does a change of physical care change Colorado child support?
Yes. Support can be modified or terminated as of the date physical care changed, up to five years before the motion unless that would be substantially inequitable.
Does the new Colorado guideline schedule change my order automatically?
No. An existing order is changed only by a modification, and the 10% test uses the guidelines at the time you file.
Official sources
- C.R.S. 14-10-122: modification and termination of support
- C.R.S. 14-10-115: child support guidelines
- C.R.S. 14-10-122 (Colorado Public Law)
- Colorado Judicial Branch: Motion to Modify Child Support (JDF 1403)
- HB25-1159: Child Support Commission recommendations (signed)
- 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 Colorado statutes, rules and court opinions, and every case turns on its own facts. Confirm how the law applies to your situation with a licensed Colorado attorney.