Spreadsheet checks before running Alimony Child Support in Illinois

What the checker catches

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

Before you run an Illinois alimony / child support spreadsheet using DocketMath, use a jurisdiction-aware “sanity check” workflow. The goal isn’t to compute final legal amounts—it’s to prevent common spreadsheet errors that can distort results and create avoidable confusion later.

DocketMath’s spreadsheet-checker is designed to catch consistency and data-quality issues before you run the alimony-child-support calculator. In practice, many problems that later look like “calculation disagreements” are really spreadsheet hygiene issues—especially around how you set the relevant time window.

In Illinois, a key example is spreadsheets that start with “number of months” (or implicitly assume a lookback period) without validating that the span aligns with the general/default limitation period you intend to use.

Here are the checks you should expect a well-structured Illinois workflow to catch:

• Missing or mismatched time boundaries

  • Example: You intend to analyze January–December, but the worksheet is set to analyze a different number of months (e.g., 60 months vs. 66 months).
• Incorrect starting point for lookback

  • Example: Using “years since separation” as a substitute for a limitation-period-backed window, without confirming the timeline is what you meant to model.
• Input units that don’t align

  • Example: Entering weekly income as if it were monthly, or entering child-related amounts in calendar years while the worksheet expects month-by-month values.
• Ambiguous date handling

  • Example: Confusing filing date, order date, and service date when your spreadsheet is designed to look back from one specific “anchor” date.
• Double-counting recurring items

  • Example: Including the same expense in both “monthly” and “annual / prorated monthly” columns.
• Negative values where they shouldn’t exist

  • Example: Net income becomes negative, but the worksheet still allocates it across categories as if it were positive (sometimes this reveals a sign/logic issue rather than a real-world outcome).
• Rounding drift

  • Example: Rounding each month and then summing vs. summing first and rounding once. The totals can differ even when the underlying inputs are the same.

Illinois limitation period awareness (why this matters)

Illinois has a general statute of limitations for certain actions of 5 years, codified at 720 ILCS 5/3-6. The Illinois General Assembly’s public act publication is here:
https://ilga.gov/ftp/Public%20Acts/101/101-0130.htm?utm_source=openai

Important: This is the general/default period. Per the brief, no claim-type-specific sub-rule was found, so the workflow should explicitly treat 5 years as the default lookback period unless you are working from a clearly identified, claim-specific rule.

In this workflow:

• Default lookback window: 5 years
• Statute cited: 720 ILCS 5/3-6
• Practical conversion: many worksheets convert 5 years to 60 months before running month-based calculations

When to run it

Run the checker before you run DocketMath’s alimony-child-support calculator, and also again after you finalize any date assumptions.

A practical cadence:

• Step 1: Before any computation

  • Lock down dates (e.g., start date, end date, order date, and any “effective from” date your model uses).
  • Confirm your spreadsheet uses one consistent timeline system (calendar months vs. days).
• Step 2: After you enter income/expense inputs

  • Verify units (annual vs. monthly, and whether annual numbers have been converted into month equivalents).
  • Ensure recurring items are represented in only one place (avoid monthly + prorated duplicates).
• Step 3: Immediately before exporting or saving results

  • Re-check rounding settings and confirm totals reconcile to line items.

A typical Illinois workflow ties the checker to timeboxing:

• If your worksheet uses a lookback window, default it to 5 years (720 ILCS 5/3-6).
• Convert consistently:

  • 5 years = 60 months, and use this consistently across your table.

Common pitfall: months changed, totals didn’t

One of the most common spreadsheet failures is updating a date that determines the number of months while forgetting to update the calculated “months of lookback.” Even a small date shift can change the month count, which changes prorations and totals.

Try the checker

You can use DocketMath’s tools here: /tools/alimony-child-support.

Recommended order of operations:

1. Open the spreadsheet-checker experience for a quick preflight review.
2. Enter or import your basic timeline assumptions and income/expense figures.
3. Fix any flagged issues (date span, unit mismatch, negative values, rounding drift).
4. Only then run alimony-child-support.

To make your testing concrete, use this checklist while you try the workflow:

How outputs change when the checks fail

When the checker flags a structural issue, the effect on results is usually predictable:

Once the checker clears these points, you can run alimony-child-support with more confidence that the spreadsheet math is structurally sound.

Related reading

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