How Interest Accrues on Unpaid Judgments

Quick takeaways

• Post-judgment interest generally starts running the day after judgment is entered and accrues until payment is made in full (or until a statutory end date or qualifying court order applies).
• The daily amount that grows each day is driven by:

  • the statutory interest rate (sometimes benchmark-based and/or reset periodically), and
  • the judgment principal (the amount owed that bears interest).
• If there are partial payments, interest often continues to accrue but on a reduced principal going forward—how that reduction is timed and calculated depends on the jurisdiction and the judgment’s components.
• DocketMath helps you model accrual as a timeline (instead of a single “big” formula), so you can generate a checkable interest total and a clear breakdown you can share.

Inputs you need

Before you use DocketMath, gather the facts that drive the math. Having these items in one place makes your results easier to verify and explain.

1) The judgment principal (what bears interest)

Identify the components that bear interest. Common buckets include:

• Damages / award amount (the core “principal”)
• Attorney fees (often treated separately; some laws include them in the interest-bearing amount, others don’t)
• Costs (court costs, filing fees; treatment varies by statute)
• Pre-judgment interest (usually handled separately from post-judgment interest)

Practical tip: If you’re unsure what counts as principal for interest purposes, enter components separately in DocketMath when possible so you can test assumptions and document what you included.

2) Judgment entry date (and time, if you have it)

You need the date interest starts. In many systems:

• Interest begins after the judgment is entered (often implemented as “from the date of judgment,” which behaves like the next day when counted in whole days).

Also consider whether there’s an interruption to accrual, such as:

• an appeal or stay,
• an order affecting enforcement,
• or other statutory exceptions.

3) Calculation end date (the “stop” date)

Choose your target end date:

• the payment date (if known),
• a cutoff date (e.g., for a payoff letter),
• or the date you’re generating the estimate for.

4) Applicable interest rate rule

Interest rates are often:

• fixed by statute (or derived from a schedule), or
• benchmark-based (e.g., a treasury yield plus spread), sometimes reset periodically.

You’ll need either:

• the rate(s) themselves, or
• the rule that determines the rate, plus the relevant reset dates.

DocketMath can handle rate changes when you model the accrual as multiple intervals.

5) Credit events (partial payments)

If partial payments occurred, gather:

• payment amount(s),
• payment date(s),
• and how/when the judgment is reduced in a way that affects future interest (timing can matter).

6) Any affecting orders (stays, enforcement changes, setoffs)

Depending on the case, these may change accrual:

• stay pending appeal,
• supersedeas bond (or equivalent protection),
• setoff or court-approved adjustments.

DocketMath’s accuracy improves when you enter these as timeline events, rather than trying to back into totals with a single “assumed” accrual period.

How the calculation works

Most post-judgment interest calculations follow a “principal × rate × time” structure, with time measured in days (or another day-count convention) and the rate expressed as an annual percentage. The specifics can vary, but the modeling logic is consistent.

Step 1: Define the accrual start and stop

• Start: typically tied to the judgment entry date
• End: the date interest stops accruing (commonly payment in full, a cutoff date, or a legal stop such as an effective stay)

If you’re estimating for a payoff on, for example, June 4, 2026, DocketMath calculates interest from the judgment entry date through that end date (based on its jurisdiction/day-count settings).

Step 2: Convert the annual rate into a daily rate

If the annual interest rate is r (as a decimal), a typical daily model is:

• daily rate = r / 365

Some jurisdictions use 360 or other conventions. If rates change over time, you’ll split the timeline into sub-periods and apply the appropriate daily rate in each sub-period.

Step 3: Apply daily interest to principal

For a single uninterrupted period with no principal reductions:

• Interest = Principal × daily rate × number_of_days

Step 4: Split into intervals when the rate changes

If the statute ties interest to a benchmark that resets (for example, annually), break the accrual into intervals:

• Interval A: start date → first rate reset date
• Interval B: reset date → payment/cutoff date

Compute interest separately for each interval using its own rate, then sum them.

Step 5: Reduce principal after partial payments (credit events)

Partial payments usually change what interest can accrue on after the payment date. A common modeling approach:

1. Compute interest from judgment entry to the first payment date
2. Reduce principal by the payment amount
3. Compute interest again from the payment date forward using the reduced principal
4. Repeat for each payment

This is where timeline modeling helps: interest “ticks” day-by-day, and the principal reduction propagates automatically.

A practical DocketMath workflow

1. Go to DocketMath tools (the modeling entry point) and start a post-judgment interest model.
2. Enter:

   • judgment principal (or components, if applicable),
   • judgment entry date,
   • payoff/cutoff date,
   • the interest rate rule (or rate input, depending on your setup).
3. Add payment events as dated credits (if any).
4. Review:

   • total accrued interest,
   • ending principal + interest,
   • breakdown by interval (for rate changes) and/or segment (for partial payments).

Common pitfalls

Even strong models produce wrong numbers when the inputs don’t match the actual rules. Watch for these recurring issues:

• Mixing pre-judgment and post-judgment interest

  • Pre-judgment and post-judgment interest often have different triggers and rates.
• Using the wrong start date

  • Confusing “verdict date,” “order date,” and “judgment entered date” can shift accrual by days or weeks.
• Assuming all components accrue at the same rate

  • Costs or attorney fees may not be interest-bearing in every jurisdiction or on every judgment.
• Ignoring partial payments

  • If you compute as though principal stayed constant after a payment, you can overstate interest.
  • Fix by entering payment dates as timeline events.
• Assuming the interest rate never changes

  • If the rate resets periodically, a single-rate calculation over multiple years can be off.
• Not accounting for stays or enforcement pauses

  • A stay pending appeal or other order can create a period where interest does not accrue (or accrues differently).

Sources and references

Post-judgment interest is governed by statute and varies by jurisdiction, often codified in state statutes and (for federal cases) in 28 U.S.C. § 1961. Key reference points commonly include:

• 28 U.S.C. § 1961 (federal post-judgment interest): sets the general framework for interest on money judgments in civil cases recovered in federal courts.
• State statutes: typically specify:

  • when interest begins,
  • the applicable rate (fixed or benchmark-based),
  • whether and when the rate resets,
  • how costs/fees are treated,
  • and how partial payments and stays affect accrual.

Because this page is not written for a specific jurisdiction, it focuses on the general modeling structure you can use and document with DocketMath.

Next steps

1. Collect your dates and amounts

   • judgment entry date,
   • principal amount (and whether costs/fees are included),
   • payoff/cutoff date,
   • partial payment dates and amounts (if any).
2. Build the model in DocketMath

   • Start at DocketMath tools
   • Enter the timeline events so principal reductions and any rate changes are reflected correctly.
3. Sanity-check the output

   • Do a rough check:

     • “interest per year ≈ principal × annual rate”
     • then scale by the fraction of a year based on the number of days.
   • If results look far off, re-check the accrual start date and what components were treated as principal.
4. Document your inputs

   • Keep a record of what you entered: principal components, date assumptions, rate settings, and any stay/stop logic. This helps with internal review and communication.
5. Re-run as settlement updates

   • If a new payment date is proposed, update the end date and (if applicable) the payment events to refresh the estimate quickly.

Related reading

• Why we started the DocketMath blog
• Introducing Explain++: step-by-step calculation breakdowns
• A practical workflow for jurisdiction-aware legal calculations (and how to document them)