Montana Child Support Calculator

How Montana calculates child support

Our record puts Montana on the Melson Formula, though that classification is our record's and has not been checked against the Montana documents this site holds, which means each parent's own basic needs are reserved first, and only the income above that reserve is available for support. Here is what that looks like in practice.

The Melson Formula is the Income Shares Model with a needs test attached to the front of it, and only three states use it. Before any support is calculated, a self-support reserve is subtracted from each parent's income. That reserve is the amount a parent needs for their own housing, food, and basic living costs, and it is protected from the calculation entirely.

Whatever income remains above the reserve is then run through two stages. First comes primary support, a per-child amount covering the children's basic needs, divided between the parents in proportion to their income above the reserve. Second comes a standard of living adjustment, which pulls an additional share of the remaining income into the order so the children share in the parents' actual circumstances rather than being held to a subsistence figure.

The practical effect is a formula that treats low and high earners very differently. A parent earning near the reserve pays little or nothing, because there is almost no income above the reserve to divide. A parent well above the reserve pays an amount comparable to an income shares state, since the standard of living stage keeps the order proportional to what the family actually earns.

What Montana protects before support is calculated

The Melson Formula sets aside an amount for each parent's own basic needs before any income is treated as available, and only income above it feeds the calculation. Montana publishes its own figure: $1,729 per month.

Primary support comes next, and Montana publishes it as a ladder by number of children rather than as a per-child amount. One child draws $519 a month and three draw $1,210, which is well short of three times the first figure. The total is divided between the parents in proportion to their income above the reserve. A standard of living allowance is added on top, so the children share in what the parents actually earn rather than being held to a subsistence figure. No percentage for it is held here for Montana, so this page states none.

What moves a Montana order

• Each parent's income above the self-support reserve
• Number of children, which sets the primary support amount
• Parenting time, in most states, under a rule we have not yet verified for this one
• Support already ordered for children from another relationship

Income limits and judicial discretion

We hold no income ceiling for Montana. What Montana's own guideline does at the top of its schedule is a question this site has not answered for this state. Courts hold authority to depart from a guideline figure when it produces an amount that does not match what the children actually need. Montana gives judges a moderate amount of room on custody and parenting time, so the final order moves with the facts of the case as well as with the arithmetic.

No child support estimate for Montana

We have withdrawn our Montana child support estimate rather than serve a figure our own measurements say is unreliable.

We are not showing you a child support figure for Montana, and this is what sits behind that. Until now this page ran on a curve of our own: one national formula standing in for the schedule each income shares state publishes. Montana's own schedule was not in it.

Here is what we found when we measured that curve, and one thing about it first. This is our own arithmetic being checked against other states' published tables, not a finding about Montana. Nobody has measured our curve against Montana, because no Montana figure is computed here from Montana's own documents to measure it against.

Checked against the eight state schedules we have transcribed, at 624 combinations of income and family size, our curve missed those schedules by 32 to 86 percent on average.

It is not wrong in one direction, which is the part that decided this. At every income from $1,500 to $6,000 a month it came in under at least one of those schedules and over another at the same time, by as much as 47 percent low and 258 percent high at a single income.

From $8,000 a month up it sat above all of them and stayed there, reaching 69 to 240 percent above those states' own tables at $30,000. Its worst region is where the dollars are largest.

A single correction would not rescue it. Because it runs low against some states and high against others at the same income, there is no factor we could multiply it by, and no direction we could honestly warn you about either. That is the line: an approximation we can point in one direction is something we can hand you with a caveat, and this one we cannot.

Knowing a figure is that far out is reason enough to stop showing it. It is not reason enough to show you a replacement this site cannot compute from Montana's own documents, so we are doing the first and not the second.

If you need a Montana figure now, Montana CSSD policy bulletin CS 404.2, effective February 1, 2026, updated January 30, 2026 is what carries it, and a Montana family law attorney or the state's own child support agency can run your figures against it. Here is what this site has on file for Montana's child support law. Montana CSSD policy bulletin CS 404.2 - read from the official copy at dphhs.mt.gov, on July 28, 2026. It is an agency publication carrying the figures, not a statute or a court rule. No Montana child support figure on this site is computed from what it holds for Montana. We will publish a Montana figure here once one can be computed from Montana's own documents, to the same standard as every other state on this site.

How parenting time changes support in Montana

Most states do reduce support when the paying parent has the children a substantial share of the year. What differs between them is not just where the line sits. It is whether there is a line at all, and whether crossing it switches the worksheet, nudges the arithmetic, or does nothing. We apply a state's parenting-time adjustment only once we have verified that state's own rule and built the mechanism behind it, and Montana is not there yet.

Four mechanisms are in use across the country, and they are not variations on one idea. The first is a cliff. Support is worked out one way below a set number of overnights and a different way at or above it, so the figure steps rather than slides. North Carolina is the clearest example and the first one our calculator computes in full, from the state's own published schedule. Its guidelines, adopted under N.C. Gen. Stat. § 50-13.4(c1), send a case to Worksheet B at 123 overnights a year, roughly 34 percent of the calendar. At 122 nights the standard worksheet applies. At 123 a different one does, and the same family can come out several hundred dollars apart on either side of that single night.

Where the line sits is not a national figure, and that is worth seeing rather than being told. Illinois runs the same kind of cliff and, for a calculation before January 1, 2027, puts it 23 nights further along: under 750 ILCS 5/505(a)(3.8) the shared care route applies where each parent exercises 146 or more overnights a year, and the basic obligation is multiplied by 1.5. We compute Illinois too. So under that rule the same family, with the same schedule, gets the adjustment in North Carolina and misses it in Illinois anywhere between 123 and 145 nights. From January 1, 2027, Illinois' Public Act 104-0733 moves its line down to 110 and adds an adjustment below 146, which the Illinois page sets out. The exact wording matters as much as the number: both of those thresholds are inclusive, so a parent sitting exactly on one qualifies, while other states word the same rule as "more than", which excludes them.

The part of a cliff rule that catches parents out is that both of them have to clear the threshold, not only the one asking for the adjustment. Work that through and the result is genuinely counter-intuitive. A parent with 250 overnights leaves the other parent 115, which sits below a 123-night bar, so the case is not shared custody under the rule at all and the shared worksheet never comes out. Getting well past an even split can cost you the adjustment an even split would have given you. If you are negotiating toward a particular number of nights, check what the schedule leaves the other parent, not only what it gives you.

The second mechanism has no line in it. Some states apply a parenting-time offset across the whole range, from the first overnight that can be determined, so every additional night moves the number a little and there is no threshold to reach. Michigan is the verified example and the second state our calculator computes in full. Under 2025 Michigan Child Support Formula Manual § 3.03 the offset applies to every support determination, so a Michigan parent with five overnights a year gets one. Guides that report a single trigger figure for a state like this are usually pointing at one of two things that are not triggers: the place where the curve steepens, which is a property of the arithmetic, or a rule about something else entirely. The 21 overnights often quoted for Michigan are the second kind. That figure governs when a change in parenting time is enough to ask a court to modify an existing order, and it has nothing to do with how the offset is worked out.

The third is no adjustment at all. Texas is the plain case: Tex. Fam. Code § 154.125 runs on the paying parent's net resources and the number of children, and the state's own official calculator has no field for overnights. Possession time reaches a Texas order only as one of the factors a court may weigh in deciding whether to depart from the guideline figure, under Tex. Fam. Code § 154.123(b)(4), and a departure can move the order in either direction.

The fourth is a formula the legislature wrote out. Georgia's parenting time adjustment became mandatory on January 1, 2026 under O.C.G.A. § 19-6-15(g), which directs the court to apply a set calculation to the noncustodial parent's basic obligation wherever a court-ordered parenting time schedule exists. That is a required step inside the presumptive calculation, not an argument made after the guideline figure is settled.

Those four produce very different answers for the same family, which is why we are not applying a general rule to Montana in the meantime. We used to. The threshold we applied was 146 nights, which is Illinois's statutory number generalised to all fifty, the size of the reduction had no legal source anywhere, and neither survived being checked, so both are gone rather than defaulted. What replaces them is each state's own rule, one state at a time, and that work has started. North Carolina's page calculates from North Carolina's published schedule and applies North Carolina's own threshold. Michigan's computes Michigan's own equations and applies an offset with no threshold at all. Illinois's reads a banded schedule keyed to net income and applies its own parenting-time rule: a 146-night cliff for a calculation before January 1, 2027, and Public Act 104-0733's 110-overnight rule from that date. Those three were done in that order on purpose: the second is the opposite mechanism to the first, and the third shares a mechanism with the first while differing from it on every number in it. We will publish Montana's parenting-time adjustment here once we have read it out of Montana's own guidelines to the same standard. Until then Montana's official child support worksheet, linked below, is where the adjusted number comes from.

Where Montana starts on parenting time

Montana does not presume equal parenting time. That is our own record rather than Montana's own custody law. Courts decide the schedule on the best interests of the children, so the overnight count is established case by case rather than assumed. Parents who expect substantial time should treat it as something to be negotiated deliberately, and should find out what Montana's own guidelines do with the count they end up with before agreeing to it.

Getting a child support order in Montana

The guideline figure is only half the picture. When the order actually arrives, and what it costs to argue about it, vary quite a bit from state to state, and both shape what a family lives on in the meantime.

Residency required, in our record

3 months

Waiting period, in our record

20 days

Uncontested, our estimate

3 months

Contested, our estimate

10 months

Support before the case is finished

Our record has 3 months of residency in Montana before you can file, and a waiting period of 20 days that has to run before a judge can finalize the divorce. States measure that period from different starting points, some from filing, some from service on your spouse, and some from the date the two of you separated, so confirm where Montana's clock begins. On our own estimates, a contested case in Montana runs 10 months, against 3 months when the parents agree. That gap is why temporary support matters. A judge can enter a temporary order early in the case, calculated on the same guideline, so the children are covered while the rest of the case is worked out. If money is tight now, a temporary order is usually the fastest relief available, and waiting for the final judgment can mean months without support.

What it costs to contest the number

On our own figures, family law attorneys in Montana run $175 to $325 an hour, and mediation costs roughly $200 a session. Worth doing the arithmetic before digging in: a handful of billable hours on each side can cost more than a full year of the amount being argued over. Where the disagreement is genuinely large, or where one parent's income is hard to pin down, representation earns its keep. Where the gap between the two positions is a few dozen dollars a month, mediation or a negotiated agreement almost always leaves both households better off. Our record carries collaborative divorce as available in all fifty states, so it says nothing specific about Montana; whether trained collaborative attorneys practise near you is a local question. Where it is on offer, both parents commit in writing to settle without litigation and use shared financial experts rather than competing ones.

Changing or enforcing a Montana order

Modifying an existing order

A child support order is not permanent, but it also does not adjust on its own. Either parent can ask the court to recalculate, and the general standard across states is a substantial and continuing change in circumstances since the last order. Job loss, a significant raise, a change in the parenting schedule, a new child support obligation for another child, and a change in the children's medical or childcare costs are the changes that most often qualify.

Two points catch parents out. The first is that a modification usually takes effect from the date the request is filed, not the date the circumstances changed, so waiting to file means absorbing the gap. The second is that the obligation continues in full until a judge signs a new order. An informal agreement between parents to pay less does not bind the court, and arrears can still accrue against the paying parent for the difference.

Enforcement

Enforcement runs through Montana's child support agency as well as the courts. Federal law requires every state to run a child support enforcement program with a common set of tools, which is why the remedies look broadly similar from state to state: income withholding straight from wages, interception of federal and state tax refunds, reporting to credit bureaus, suspension of driver's and professional licenses, liens against property, and contempt proceedings for willful non-payment. Income withholding is the default for new orders in most cases rather than a penalty applied after a missed payment.

Montana guideline authority and official worksheet

What we hold for Montana, with what it is and how we hold it. It is not named here as the text that controls:

• Montana CSSD policy bulletin CS 404.2 - read from the official copy at dphhs.mt.gov, on July 28, 2026. It is an agency publication carrying the figures, not a statute or a court rule.

We are not showing a Montana estimate, so the state's own courts and child support agency are where a figure has to come from for now.

Montana prints the working figures in a Child Support Services Division policy bulletin, and bulletin CS 404.2 is where the current dollar amounts are. Montana does not use the term "self-support reserve" that most states do: the bulletin calls the parent's protected amount the Personal Allowance, so a search for the more common phrase in Montana's own materials returns nothing.

The figures move every February 1, pegged to the federal poverty guidelines and the IRS standard mileage rate. That is a faster clock than the four-year review most states run on, so a Montana figure has a twelve-month shelf life by design and a bulletin from a previous February is out of date rather than merely old.

Both allowances are stated per year rather than per month, which is the opposite of most states and is the single easiest thing to get wrong when comparing Montana with anywhere else. The personal allowance is $20,748 a year, which is $1,729 a month. The primary child support allowance runs from $6,224 a year for one child to $20,748 for six, and it is a ladder rather than a per-child amount: two children draw $10,374 rather than twice the one-child figure.

Where to get the official worksheet

Every state publishes a child support worksheet or an official calculator, and that document is what a judge or the state agency works from. We do not yet have a verified direct link to Montana's worksheet, so the starting points below are the state's own court site and the federal directory of state child support agencies rather than a deep link we cannot vouch for.

• Montana courts , the state judiciary site from our Montana source record.
• Office of Child Support Services, U.S. Administration for Children and Families, which maintains the directory of state child support agencies.
• National Conference of State Legislatures, child support guideline models by state, which publishes its own comparison of the guideline model each state uses, so you can check ours against it.

How we calculate this estimate

This page does not produce a child support figure for your state, and the panel above sets out why in full. The short version: a guideline figure on this site is computed from the state's own published guideline, and no figure for your state is computed from the documents this site holds for it, which the authority section on this page names. What we were showing until recently was built by us to stand in for one, and we would rather show you nothing than show you that.

What this page does instead for Montana

• It sets out what your state's guideline is recorded as doing, and says plainly which parts of that record somebody has checked against a document and which parts nobody has.
• It says what we were previously calculating, and what we found when we looked at it. That finding is the part you can use, whether or not we ever publish a figure here.
• It points at the document that carries the real answer where we can name one, and says so where we cannot rather than sending you to a citation nobody here has opened.
• Nothing on this page is a dollar amount for your family. The other calculators on this site still run for your state, and the filing fees and waiting periods on your state page are unaffected by any of this.

Where to get the real number

Your state's own worksheet is the controlling document, and it is the thing to work from. A licensed family law attorney in your state, or your state's child support agency, can run your figures against it and tell you what a court would be starting from.

Read the full methodology for how every calculator on the site is built.

Sources

Montana courts and statutes

Citations our record carries for Montana. Being listed here does not mean a figure on this page was read from it.

• courts.mt.gov
• Montana CSSD policy bulletin CS 404.2
• ARM 37.62.114
• ARM 37.62.121

Where to read more

Background reading. No number on this page is taken from any of these.

• National Conference of State Legislatures, child support guideline models by state
• Office of Child Support Services, U.S. Administration for Children and Families
• American Bar Association, Section of Family Law

About this page

Written by Barron Hansen

I am an app developer who is dedicated to building the highest-value, most accurate web apps possible, that people want to use every day.