Worked example: Alimony Child Support in Illinois

Example inputs

Run this scenario in DocketMath using the Alimony Child Support calculator.

This worked example shows how DocketMath (jurisdiction-aware for Illinois, US-IL) can help you model payments that combine child support and alimony. This is a calculation walkthrough, not legal advice, and it won’t replace an attorney’s review of your case facts (especially ages of children, incomes, health-care allocations, and any deviation requests).

If you want to run this scenario yourself, start at: /tools/alimony-child-support.

Scenario (inputs you would enter into DocketMath)

Assume the following monthly amounts and dates:

• Start of support obligation: 2024-02-01
• Number of children: 2
• Child’s ages: 6 and 10
• Parent A (paying parent) gross monthly income: $6,800
• Parent B (receiving parent) gross monthly income: $5,200
• Any additional child-related monthly costs (input field, if applicable): $0
• Parent A gross monthly income used for alimony model: $6,800
• Parent B gross monthly income used for alimony model: $5,200
• Alimony “duration assumption” in the tool: 48 months
• Alimony “monthly rate setting” in the tool: $650/month
• Payment frequency: Monthly
• Arrearage / enforcement lookback window: 5 years (default)

Key Illinois rule used for the enforcement window (time limitation)

DocketMath applies a general/default lookback period unless your situation clearly triggers a different, claim-specific rule.

• General Illinois limitations period: 5 years
• Statute: 720 ILCS 5/3-6
• Source: https://ilga.gov/ftp/Public%20Acts/101/101-0130.htm?utm_source=openai

What the tool will compute (high level)

You’ll generally see three outputs:

1. **Estimated child support amount (monthly)
2. Estimated alimony amount (monthly) based on the tool’s model/rate inputs
3. Estimated total monthly support = child support + alimony
   (plus an optional 5-year arrearage window view, depending on how you configure the tool)

If your inputs or the tool’s fields differ (e.g., net vs. gross, or whether you supply a preset alimony rate), the outputs will change accordingly.

Example run

Below is what happens in one consistent run using the inputs above. Exact figures depend on the internal mechanics of the alimony-child-support calculator, but the workflow and relationships among the numbers are what matter most.

Run the Alimony Child Support calculator using the example inputs above. Review the breakdown for intermediate steps (segments, adjustments, or rate changes) so you can see how each input moves the output. Save the result for reference and compare it to your actual scenario.

1) Compute child support (monthly)

DocketMath uses the income inputs you provide (Parent A: $6,800; Parent B: $5,200) and the number/ages of children (two children ages 6 and 10) to estimate the monthly child support figure.

Run result (illustrative):

• Estimated child support: $1,950/month

2) Compute alimony (monthly)

For alimony, this example uses:

• Alimony model duration: 48 months
• Alimony monthly rate input: $650/month

Run result (illustrative):

• Estimated alimony: $650/month

3) Combine into total monthly support

Total monthly support is typically the sum of:

• child support ($1,950)
• alimony ($650)

Run result (illustrative):

• Estimated total monthly support: $2,600/month

4) Add an enforcement / lookback window (5 years)

Because this worked example uses the general/default 5-year period, the arrearage lookback window is:

• Start date: 2024-02-01
• Lookback duration: 5 years
• Window length: about 60 months

Window-style total (illustrative):

• Estimated total over 5 years:
  $2,600/month × 60 months = $156,000

This “window total” is a modeling view—it assumes the same monthly obligation each month across the period. In real cases, incomes, custody arrangements, or adjustment triggers may change payment amounts.

Sensitivity check

Small changes to a few inputs can produce noticeably different outputs. Use the checklist below to run quick “what-if” tests in DocketMath and understand which levers matter most.

A. Change Parent A income (paying parent)

Run two variants:

• Variant 1: Parent A income $6,800 (baseline)
• Variant 2: Parent A income $7,300 (+$500)

Expected direction:

• Child support tends to increase when the paying parent’s income increases relative to the receiving parent.
• Alimony may also increase, depending on how the tool uses the alimony inputs/rate.

Quick test checklist

B. Change Parent B income (receiving parent)

Try:

• Variant 1: Parent B $5,200 (baseline)
• Variant 2: Parent B $4,600 (-$600)

Expected direction:

• Lower receiving-parent income can lead to a higher child support estimate, because the income ratio changes.
• Alimony may change depending on the tool’s alimony model/rate logic.

C. Change number/ages of children

This worked example uses children ages 6 and 10. Now test:

• Variant: change ages to 12 and 15 (keeping the number of children constant)

Expected direction:

• Child support calculations often reflect age-based considerations.
• If DocketMath’s model uses age categories, the estimate will adjust.

Checklist to confirm your setup:

D. Change the alimony duration assumption (without changing monthly rate)

If you keep:

• alimony monthly rate input at $650
• but change duration from 48 months to 36 months

Expected direction:

• Your monthly total may remain roughly the same in the model.
• A “total over window” view may change if the tool prorates or limits alimony by duration in its arrearage-style calculation.

E. Confirm the enforcement window logic (5 years)

Because the example uses 720 ILCS 5/3-6 as the general default:

• General SOL: 5 years

You can sanity-check the tool’s time window by verifying:

For completeness, the statute used here is:

• 720 ILCS 5/3-6
• Source: https://ilga.gov/ftp/Public%20Acts/101/101-0130.htm?utm_source=openai

Related reading

• Alimony & Child Support Estimator Guide for Alabama
• Alimony & Child Support Estimator Guide for Arizona
• Alimony & Child Support Estimator Guide for Colorado