How to Calculate Arkansas Child Support for Shared Custody (AO10 Offset Method)

If you have shared custody in Arkansas — meaning the child spends 141 or more overnights per year with each parent — your child support isn't calculated using the standard formula. Arkansas Administrative Order No. 10 (AO10) uses a completely different method called the offset calculation, and the difference can be hundreds of dollars per month. Most parents don't discover this until mediation or their first court hearing, when the numbers don't match what they expected.

Here's exactly how the offset method works, when it applies, and why the difference between 140 and 141 overnights matters more than most parents realize.

The 141-Overnight Threshold

AO10 draws a hard line at 141 overnights per calendar year:

• Under 141 overnights: Standard calculation. The non-custodial parent pays their proportional share of the Basic Child Support Obligation (BCSO) to the custodial parent. No adjustment for time spent.
• 141+ overnights: Offset method. Both parents' obligations are calculated separately, and the parent who owes more pays the difference to the other parent.

This isn't a sliding scale. There's no partial credit for 120 overnights or 135 overnights. The switch happens at exactly 141.

Why This Threshold Changes Everything

Consider two parents with a combined gross monthly income of $8,000 and one child. Under AO10's chart, their Basic Child Support Obligation (BCSO) is approximately $1,026.

Parent A earns $5,000/month (62.5% of combined income) Parent B earns $3,000/month (37.5% of combined income)

At 140 overnights (standard method):

• Parent A's share: $1,026 × 62.5% = $641/month
• Parent A pays $641 to Parent B
• No adjustment for the 140 overnights Parent A actually has the child

At 141 overnights (offset method):

• Parent A's obligation (calculated as if non-custodial): $1,026 × 62.5% = $641
• Parent B's obligation (calculated as if non-custodial): $1,026 × 37.5% = $385
• Offset: $641 − $385 = $256
• Parent A pays $256 to Parent B

One overnight changes the monthly support by $385.

This is why counting overnights precisely matters. A parent proposing a schedule at 139 overnights is leaving hundreds of dollars per month on the table compared to a schedule at 142 overnights — or paying hundreds more, depending on which side of the threshold they're on.

Step-by-Step: The Offset Calculation

Step 1: Determine Combined Gross Monthly Income

Add both parents' gross monthly incomes (before taxes, including wages, commissions, bonuses, self-employment income, rental income, and most government benefits).

• Parent A gross monthly: $______
• Parent B gross monthly: $______
• Combined: $______

Step 2: Find the Basic Child Support Obligation (BCSO)

Look up the combined gross monthly income on the AO10 Family Support Chart (available from the Arkansas Judiciary website or your circuit clerk). The chart provides a BCSO amount based on combined income and number of children.

Step 3: Calculate Each Parent's Income Percentage

• Parent A percentage: (Parent A income ÷ Combined income) × 100 = ______%
• Parent B percentage: (Parent B income ÷ Combined income) × 100 = ______%

Step 4: Calculate Each Parent's Obligation

This is where the offset method diverges from standard. Instead of calculating only the non-custodial parent's share, you calculate both:

• Parent A's obligation: BCSO × Parent A's percentage = $______
• Parent B's obligation: BCSO × Parent B's percentage = $______

Step 5: Subtract the Lower from the Higher

• Higher obligation: $______
• Lower obligation: $______
• Offset amount: Higher − Lower = $______

The parent with the higher obligation pays the offset amount to the other parent.

Step 6: Add Proportional Shares of Mandatory Add-Ons

Both calculation methods require adding:

• Health insurance premiums for the child (divided by income percentage)
• Work-related childcare costs (divided by income percentage)

These add-ons are allocated the same way regardless of whether you're using the standard or offset method.

Step 7: Check the Self-Support Reserve

AO10 protects low-income parents through the Self-Support Reserve (SSR). If the paying parent's gross monthly income falls below $900 after the calculated obligation is deducted, the court applies a presumptive minimum order of $125 per month. This floor applies to both standard and offset calculations.

Common Schedules and Their Overnight Counts

The schedule you propose directly determines whether you're in the standard or offset tier:

Note that even with Act 604's presumption of approximately equal parenting time, many agreed schedules produce overnights in the 130–145 range depending on how mid-week visits and summer blocks are structured. The overnight count isn't intuitive — you have to map it on a calendar.

The Mistakes Parents Make

Mistake 1: Assuming equal time means equal overnights

A schedule that feels like "50/50" on paper can produce anywhere from 130 to 190 overnights depending on how transitions, summers, and holidays are structured. The only way to know is to count.

Mistake 2: Forgetting that holidays override the regular schedule

Holiday rotations typically override the weekly schedule. If your regular rotation produces 145 overnights but the holiday schedule gives the other parent an extra week at Christmas and spring break, you might drop below 141.

Mistake 3: Not calculating both scenarios before mediation

Walking into mediation knowing what child support looks like at 140 overnights AND at 142 overnights gives you negotiating information. Walking in with only a vague schedule means discovering the financial implications after you've already agreed to the terms.

Mistake 4: Using a different state's calculator

Online child support calculators for other states don't use Arkansas's AO10 Income Shares Model. Arkansas's specific chart, threshold, and offset mechanics are different from neighboring states like Missouri, Oklahoma, Tennessee, and Texas. Use the AO10 chart or an Arkansas-specific worksheet.

Who This Is For

• Parents proposing a shared custody schedule who need to understand the financial implications
• Parents in mediation trying to evaluate whether adjusting one or two overnights changes their child support outcome
• Self-representing filers who need to complete the AO10 child support worksheet for the court
• Parents whose proposed schedule falls near the 141-overnight boundary

Who This Is NOT For

• Parents with combined gross monthly income above $30,000 (the AO10 chart doesn't extend beyond this — judicial discretion applies)
• Cases involving imputed income disputes where one parent is voluntarily unemployed or underemployed (these require legal arguments beyond worksheet math)
• Parents seeking to modify an existing child support order (modification requires showing a material change in circumstances)

Run Your Own Numbers

The Arkansas Child Custody & Parenting Plan Guide includes AO10 child support worksheets for both the standard and offset methods, parenting schedule templates with pre-calculated overnight counts, and a side-by-side comparison showing exactly how crossing the 141-night threshold changes your obligation. For , you can run every scenario before mediation instead of discovering the math after you've agreed to terms.

Frequently Asked Questions

Does the 141-overnight rule apply to all Arkansas custody cases?

Yes. AO10 applies statewide to all child support calculations in Arkansas, whether the case arises from divorce, paternity, or a standalone custody petition. The 141-overnight threshold is a fixed feature of the Income Shares Model.

What counts as an "overnight" under AO10?

An overnight is any period where the child sleeps at the parent's residence. If the child is dropped off at 7 PM and picked up at 7 AM, that's one overnight. Daytime-only visits don't count toward the overnight total.

Can the judge deviate from the AO10 calculation?

Yes. AO10 creates a presumptive obligation that the court can adjust based on the child's specific needs, extraordinary medical expenses, or other factors. However, deviations must be documented in the court order with specific findings. Judges don't deviate without a stated reason.

What if we agree to a different child support amount than AO10 calculates?

Parents can agree to an amount different from the AO10 calculation, but the court must approve it. If the agreed amount is below the AO10 guideline, the judge will require a written explanation of why the deviation serves the child's best interest. The court retains the right to reject agreements that deviate too far from the calculated obligation.

How do I count overnights for a schedule that changes seasonally?

Map the schedule across an entire calendar year — regular school-year rotation plus summer break schedule plus holiday overrides. The annual total is what matters for the 141-night threshold, not the per-week average. School-year and summer schedules often produce different weekly patterns, so a monthly or quarterly count won't give you the right number.

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