Tennessee calculates child support using the income shares model: both parents’ adjusted gross incomes are combined, run against a state schedule to get a base obligation, then split in proportion to what each earns. That base number is adjusted for parenting time and add-ons like health insurance and childcare. You can plug in your own numbers with our free child support calculator before sitting down with the official state worksheet.
The rules are the Tennessee Department of Human Services (DHS) Child Support Guidelines, Tenn. Comp. R. & Regs. Chapter 1240-02-04. The current version took effect October 1, 2021 and is published in full by the Tennessee Secretary of State. What follows is an orientation, not a substitute for reading the guidelines or talking to a lawyer.
The formula, step by step
- Determine each parent’s gross income, then subtract allowed adjustments (self-employment taxes, credit for other qualified children) to get Adjusted Gross Income (AGI).
- Combine both parents’ AGI.
- Look up the Basic Child Support Obligation (BCSO) on the state’s Schedule, using combined AGI and the number of children (Rule 1240-02-04-.09).
- Prorate the BCSO between the parents by each one’s share of combined AGI.
- Apply the parenting-time adjustment for the alternate residential parent (ARP).
- Add the child’s health insurance premium, work-related childcare, and recurring uninsured medical expenses, prorated the same way (Rule 1240-02-04-.04(8)).
- Run the self-support reserve check if the paying parent’s income is low.
- Arrive at the Presumptive Child Support Order (PCSO) — the number the court uses unless a deviation applies.
What counts as income
Tennessee’s definition of gross income is broad. Under Rule 1240-02-04-.04(3), it reaches wages, salaries, commissions, tips, self-employment income, bonuses, overtime, severance, pensions, Social Security and VA benefits, interest, dividends, capital gains, workers’ compensation, unemployment benefits, personal injury judgments, gifts and inheritances convertible to cash, prizes and lottery winnings, and alimony from someone other than the other parent. Variable income like commissions and overtime is averaged over a reasonable period rather than pinned to one pay stub. Excluded: child support received for children of another relationship, the child’s own income, and means-tested benefits like TANF, SNAP, and SSI.
If a parent isn’t working, or appears to be working below capacity, the court can impute income based on the parent’s past and present employment and their education and training. The Guidelines state that no parent is presumed willfully underemployed or unemployed — a tribunal has to make that finding on the facts. Incarceration is not treated as willful underemployment, and the finding is not made against someone who enlists, is drafted, or is activated for full-time military service.
The parenting-time adjustment
The guidelines presume a “standard” arrangement — the ARP has the children a total of 80 days a year (every other weekend, two weeks in summer, two weeks of holidays). Time different from that shifts the number, under Rule 1240-02-04-.04(7):
- 92 days or more: a formula (the “variable multiplier”) credits the ARP for costs they now cover directly — the net effect is a lower payment.
- 68 days or fewer: the obligation may increase, reflecting that the primary residential parent (PRP) covers nearly all day-to-day costs.
- 69–91 days: no adjustment either way.
A “day” of parenting time means the child spends more than 12 consecutive hours in a 24-hour period in one parent’s care, control, or direct supervision, per Rule 1240-02-04-.02(10); that period need not match the calendar day, and only one parent can claim credit for it. With multiple children on different schedules, the worksheet averages across all of them. These adjustments are presumptive rather than mandatory — the rule allows the presumption to be rebutted by evidence.
Add-ons: insurance, childcare, medical
The BCSO covers ordinary child-rearing costs — housing, food, transportation, clothing, basic school expenses. It excludes the child’s health insurance premium, work-related childcare, and recurring uninsured medical expenses; those are added on top and split pro rata by income share. Extraordinary education costs and “special expenses” like camp or extracurriculars are added only as a deviation, and the rule directs the tribunal to consider special expenses when that category exceeds 7% of the monthly BCSO (Rule 1240-02-04-.07(2)(d)2).
Low income and the self-support reserve
Tennessee builds in a self-support reserve (SSR) so a low-income paying parent keeps enough to meet their own basic needs. The SSR is $957 in monthly gross income — 90% of the 2020 federal poverty level for one person, per Rule 1240-02-04-.03(4)(b). If the paying parent’s income falls in the SSR “shaded area” of the schedule, the worksheet compares the obligation computed on that parent’s income alone against the standard calculation and takes the lower amount. One consequence: the rule states that where the SSR is applied, the obligor does not receive the parenting time credit. Separately, Rule 1240-02-04-.05(6) sets a minimum order of at least $100 per month, with listed exceptions — including where the obligor’s only income is SSI — and the court keeps discretion to set it higher or lower.
Deviations from the standard calculation
The Presumptive Child Support Order is a rebuttable presumption. A court can deviate up or down under Rule 1240-02-04-.07, but must put its reasoning in writing, including what the order would have been without the deviation. Grounds named in the rule include extraordinary educational expenses, special expenses over the 7% threshold, substantial parenting-time travel costs, and extreme economic hardship such as extraordinary uninsured medical needs. The rule also sets a floor: no deviation may seriously impair the primary residential parent’s ability to maintain minimally adequate housing, food, and clothing for the children supported by the order.
Get an estimate before you file. Our free child support calculator uses the same income-shares inputs Tennessee’s worksheet does, so you can see roughly where you’d land.
Modifying an existing order: the significant variance rule
Once a Tennessee order is in place, changing it takes a “significant variance” between the current order and what the guidelines would produce today. Under Rule 1240-02-04-.05(2), that means at least a 15% difference between the current support obligation and the proposed one. For orders calculated under the income shares guidelines, you compare Presumptive Child Support Order amounts and leave out any previously ordered or proposed deviation.
One point worth flagging, because it turns up in a lot of secondary write-ups: you will still see a 7.5% “low-income provider” variance quoted for obligors at or below the federal poverty level. That figure comes from the pre-2020 version of this rule. The current text, amended effective May 10, 2020 and recompiled effective October 1, 2021, defines significant variance only as 15% and contains no separate low-income percentage. The enabling statute, T.C.A. § 36-5-101(e), contemplates a low-income variance set by department rule at no more than 7.5%, but the department has not carried one into the current guidelines. If you’re working from an older article or form citing 7.5%, check it against the rule text.
A change in the number of children owed support, a parenting-time change, or a childcare cost change can also justify modification if it clears the variance threshold. One exception: the child’s health care needs are a basis for modification regardless of dollar variance. Modifications aren’t retroactive — they run from the date the action is filed and notice is mailed, not from when the change happened.
The worksheets and where to get them
Tennessee orders are calculated on DHS’s official Child Support Worksheet and, where relevant, the Credit Worksheet. The rule makes their use mandatory and requires completed worksheets to be kept as part of the official record. DHS offers an Excel worksheet, a step-by-step web calculator, and an iOS app on its Child Support Calculator page, plus A Guide to Tennessee’s Child Support Worksheet. DHS is explicit that the calculator is for educational and informational purposes only, and that only a court or other tribunal can set child support.
FAQ
Is overtime counted as income in Tennessee child support?
Yes. Overtime, bonuses, and commissions are all gross income under Rule 1240-02-04-.04(3), and because they fluctuate, the rule has them averaged over a reasonable period.
What happens if a parent is unemployed?
The court looks at why. If a tribunal finds a parent willfully underemployed or unemployed, income can be imputed based on that parent’s past and present employment and their education and training. Among the factors the rule directs tribunals to weigh are a parent’s stay-at-home caretaker role and their role caring for a seriously ill or disabled child or relative.
How often can child support be modified in Tennessee?
The rule sets no fixed waiting period, but a modification requires a “significant variance” — at least a 15% difference between the current order and what the guidelines produce now. Either parent can request a review, but a filing without a qualifying change has nothing to work with.
Where the book fits in
Formula mechanics are only part of building a case yourself — you’ll also need income documentation, a correctly completed worksheet, and a sense of what evidence a court expects for a deviation or modification. The Navigating Child Support book covers the process state by state, including Tennessee, and comes with a code for a free forms packet.
This article is for general information only and isn’t legal advice. Child support law changes, and how it applies to your situation depends on facts a website can’t account for. For anything beyond a rough estimate, talk to a licensed Tennessee family law attorney or your local court’s self-help center.
