What child support actually depends on.
Not what you earn. How many nights the children sleep at your house — and the exact number your state has decided matters.
Every state calculates child support with a published formula, and almost every state publishes the formula for free. The differences between them are much larger than anyone expects — and the single biggest one is not income. It is how many nights the children spend with each parent, and where that state draws the line.
All fifty states
The overnight column is the threshold at which the amount starts to change. Where a state counts days or percentages rather than overnights, the column says so rather than converting — the guidelines are not interchangeable and neither are the units.
| State | Model | Overnight trigger | Court can order college | Calculator |
|---|---|---|---|---|
| Alabama | Income shares | 50/50 only | Narrow route | Official |
| Alaska | Percentage of income | 110 nights | No | Official |
| Arizona | Income shares | 20 days | No | Official |
| Arkansas | Income shares | 141 nights | Not confirmed | Official |
| California | statutory algebraic formul | In the formula | Only if agreed | Official |
| Colorado | Income shares | Every overnight | Not confirmed | Official |
| Connecticut | Income shares | No count | Yes | Official |
| Delaware | Melson formula | 164 nights | No | Official |
| Florida | Income shares | 73 nights | No | Official |
| Georgia | Income shares | Every day counts | No | Official |
| Hawaii | Income shares | 144 nights | Yes | Official |
| Idaho | Income shares | 91 nights | No | Official |
| Illinois | Income shares | 146 nights | Yes | Official |
| Indiana | Income shares | 52 nights | Yes | Official |
| Iowa | Income shares | 128 days | No | None published |
| Kansas | Income shares | 35% of time | Only if agreed | Official |
| Kentucky | Income shares | 88 nights | No | Official |
| Louisiana | Income shares | Over 73 days | No | Official |
| Maine | Income shares | Equal care only | No | Official |
| Maryland | Income shares | 92 nights | Not confirmed | None published |
| Massachusetts | Income shares | Built in | Yes | Official |
| Michigan | Income shares | No cliff | No | None published |
| Minnesota | Income shares | No cliff | No | Official |
| Mississippi | Percentage of income | No credit | Narrow route | None published |
| Missouri | Income shares | 36 nights | Yes | None published |
| Montana | Melson formula | 110 days | Only if agreed | Official |
| Nebraska | Income shares | 142 days | No | Official |
| Nevada | Percentage of income | Joint custody only | No | Official |
| New Hampshire | Income shares | 35% of time | No | Official |
| New Jersey | Income shares | Separate worksheet | Yes | None published |
| New Mexico | Income shares | 127 days | Not confirmed | Official |
| New York | Percentage of income | No formula | Yes | None published |
| North Carolina | Income shares | 123 nights | No | Official |
| North Dakota | Percentage of income | 100 nights | Narrow route | Official |
| Ohio | Income shares | 90 nights | Only if agreed | None published |
| Oklahoma | Income shares | 121 nights | No | Official |
| Oregon | Income shares | Every overnight | Yes | Official |
| Pennsylvania | Income shares | 40% of time | Unsettled | None published |
| Rhode Island | Income shares | 49% each | No | Official |
| South Carolina | Income shares | 110 nights | Not confirmed | None published |
| South Dakota | Income shares | 6 nights a month | Not confirmed | Official |
| Tennessee | Income shares | 92 days | No | Official |
| Texas | Percentage of income | No credit | Not confirmed | Official |
| Utah | Income shares | 110 nights | No | Official |
| Vermont | Income shares | 30% of nights | No | Official |
| Virginia | Income shares | 90 days | No | Official |
| Washington | Income shares | Judge's discretion | Yes | Official |
| West Virginia | Income shares | 127 days | Yes | None published |
| Wisconsin | Percentage of income | 92 nights | No | Official |
| Wyoming | Income shares | No credit | Not confirmed | Official |
No state matches that.
One warning about the college column. “Yes” means a court has authority to order it — not that it will. And in every state on this list, including the ones that say no, parents can agree to cover college in writing and have that agreement enforced. If college matters to you, the written agreement is the reliable route everywhere. The court’s authority is the fallback, and in most of the country there is not one.
Three things worth knowing before you read your own state
The overnight number is negotiable, and it is worth money
In most states there is a specific figure — 88, 92, 110, 123, 146 — where the amount changes. A parenting schedule landing one night on the wrong side of it can be worth thousands a year. Very few people know the number before they agree the schedule. Yours is on your state’s page.
The state’s own calculator is free
Where a state publishes one, it is linked above and it costs nothing. Anyone charging you for a child support calculation in those states is charging for arithmetic the court already published.
Support does not stop by itself everywhere
In some states it ends automatically. In others somebody has to file, and until they do the obligation keeps running — including where a child in a multi-child order ages out. Your state’s page says which.
Start at when they stop paying, which answers the questions in order. Then filing for contempt for the court route and how to file it yourself, and support arrears for the enforcement tools that do not need a hearing — license suspension, passport denial and interception. If it is alimony rather than child support, the state will usually not collect it for you: enforcing alimony is the harder road.
Start at when you cannot pay child support — and file to modify today rather than this month. A court generally cannot reduce arrears that have already built up, so the date you file is the line between debt you can still argue about and debt you cannot. Changing the support number is the filing itself; support arrears is why the date matters.
Neither one? Child support by state has the rules where you live, and securing support covers what happens if the person paying dies or becomes disabled.