Post-Judgment Interest Rates by State

Quick takeaways

• Post-judgment interest is governed by state statutes, and most states structure the rate using one of these mechanics:

  • a static annual rate,
  • a rate tied to a market benchmark (e.g., Treasury or a published rate), or
  • a sliding rate that resets at defined intervals.
• Many states calculate interest on the judgment amount (principal) from a specific trigger date, such as:

  • the date of judgment,
  • the date of entry, or
  • the date the judgment becomes final.
• For multi-issue judgments, the most common “rate” mistakes come from:

  • using the wrong base amount (what interest applies to), or
  • starting interest on the wrong date (which changes the interest window).
• DocketMath helps you preserve the rate rule, base, and interest window so you can reproduce the calculation later—especially when the rate changes during the life of a case.

Inputs you need

DocketMath is designed to produce consistent results when you provide the same core inputs each time. For post-judgment interest, the key inputs are:

1) State (and judgment context)

• State (jurisdiction) where the judgment was entered.
• Whether the judgment is state-court and how the money award is characterized (for example, a damages award only vs. an award that also includes costs/fees).

2) Principal (the amount interest applies to)

• The principal amount (often the “judgment” number excluding interest).
• If the judgment includes items like costs or attorney fees, capture how your state treats those items for the interest base (some states restrict the base; others may allow certain components).

3) Trigger date for interest

Choose the date that matches the statute’s language and the court’s procedure. Common candidates include:

• Date of judgment
• Date of entry
• Date a judgment becomes final (sometimes after post-trial motions or after appeal-related timing)

4) End date (when you’re computing to)

Interest calculations need a stopping point:

• Payment date (if known), or
• An as-of date for demand/settlement or internal analysis.

5) Rate mechanic (what the state statute uses)

States differ on whether the rate is:

• Fixed (the same rate for the entire post-judgment period), or
• Benchmark-based (rate changes according to a published benchmark or periodic schedule)

If the statute resets the rate, you also need:

• Reset frequency (annual, quarterly, semiannual, etc.)
• Effective dates for each published rate period

How the calculation works

Post-judgment interest is usually computed with a formula that follows this general pattern:

• Simple interest: Principal × Rate × Time
• If the rate changes: split the timeline into rate periods, then compute and sum interest for each period.

Even though each state has its own statutory phrasing, the computational pattern is often the same: define the interest window, then apply the correct rate(s) over that window.

Step-by-step workflow (rate periods + date math)

1. Identify the interest window

   • Start on the state’s statutory trigger date.
   • Stop on your as-of date or payment date.
   • Example structure (illustrative only):

     • Start: 2024-05-10
     • End: 2026-06-04
     • Total window: 755 days (the exact day-count convention can vary by jurisdiction—use the method stated or applied by the jurisdiction)

2. Determine whether the interest rate changes

   • If the state uses a single fixed rate, apply it to the entire window.
   • If the state uses a benchmark with periodic updates, split the window into segments that match each rate’s effective period.

3. Compute interest for each segment For each segment with rate r:

   • Segment Interest = Principal × r × (days in segment / days per year)
   • Many jurisdictions express rates as an annual percentage rate (APR), so the “days per year” convention matters (commonly 365, but sometimes other conventions are used). Follow the jurisdiction’s method.

4. Sum segment totals

   • Total Post-Judgment Interest = Σ Segment Interests

5. Add interest to principal if required (or separate it)

   • Some states require interest to be tracked separately for reporting purposes, even if it ultimately gets paid together.
   • DocketMath can keep principal, interest, and total distinct so you can audit what went into the number.

DocketMath: documenting the rate and timing

DocketMath’s main advantage for post-judgment calculations is repeatability. When rates reset, you want a clear trail showing:

• the rate used,
• the effective period for that rate,
• the start/end dates of the segment, and
• the principal base.

This helps prevent “spreadsheet drift,” where a revised spreadsheet unintentionally changes an assumption (like using today’s rate for an old window).

Common pitfall: If a state updates its post-judgment interest rate midstream (e.g., annually), applying only the most recent rate for the entire period can materially overstate or understate total interest.

Common pitfalls

1) Using the wrong start date (judgment vs. entry vs. finality)

Courts and statutes may use different terms for when interest begins to accrue. Missing the correct trigger date can shift the window by weeks or months.

Checklist:

• Is the start date date of judgment, date of entry, or date of finality?
• Did post-trial motions affect finality timing?
• Did appeal posture change when the judgment became “final” under the statute?

2) Assuming interest accrues on everything included in the judgment

Some states calculate interest on the judgment principal only, while others may allow interest on certain additional components. Costs and attorney fees are common “base” differences.

Checklist:

• Does your state statute define the interest base as principal only, or include other award components?
• If costs/fees are included in the award, does the statute specify whether they are part of the base?

3) Forgetting rate resets

If the statute ties the rate to a benchmark or resets it periodically, a single-rate calculation can silently go wrong.

Checklist:

• Does the statute require periodic rate resets?
• Did you split the timeline into the correct rate periods?
• Did you use the correct effective dates for each reset?

4) Confusing post-judgment interest with prejudgment interest

Prejudgment interest often has different rules and triggers. Post-judgment interest typically starts only after the court has fixed liability/amount.

Checklist:

• Are you calculating post-judgment interest only?
• Does the judgment (or applicable law) indicate the interest category being applied?

5) Day-count conventions (365 vs. 360 vs. other methods)

Even with the right rates and dates, totals can shift depending on the day-count convention used to compute time.

Checklist:

• Does the state statute or governing practice specify the day-count method?
• Did DocketMath apply that convention consistently across segments?

Sources and references

This section focuses on how to verify the governing rule, since post-judgment interest varies significantly by jurisdiction.

When documenting your calculation, use these verification targets:

• State post-judgment interest statute (the controlling section typically provides):

  • the rate method (fixed vs benchmark/sliding),
  • the trigger date (judgment/entry/finality),
  • and the definition of the interest base (principal only vs additional components).
• Published benchmark documentation (if the statute ties interest to a Treasury/index or similar published rate).
• Court rule definitions relevant to:

  • “entry of judgment,”
  • finality,
  • and enforceability timing.

Next steps

1. Pick the jurisdiction where the judgment was entered.
2. Extract the principal/base amount that matches what the statute treats as the interest base.
3. Lock the interest start date to the statute’s trigger (judgment/entry/finality).
4. Choose your calculation end date (payment date or a defined as-of date).
5. Identify whether the rate resets during the window:

   • If yes, split the timeline into rate periods and compute interest per period.
6. Run the calculation in DocketMath and save:

   • the state rate rule you used,
   • the rate periods (with effective dates),
   • and the start/end dates applied to each segment.

If you want to move faster, start here: /tools.

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)