Worked example: interest in North Carolina
7 min read
Published December 19, 2025 • Updated February 2, 2026 • By DocketMath Team
Worked example: interest in North Carolina
This walkthrough shows how a simple interest calculation might look for a North Carolina matter using DocketMath’s interest calculator. It’s not legal advice—just a concrete, numbers-first example you can adapt to your own workflow and documentation.
We’ll:
- Specify realistic inputs
- Run the numbers step by step
- Stress‑test the result with a few “what if” changes
- Flag where legal judgment, not just math, usually comes in
Example inputs
Assume you’re tracking prejudgment interest on a money judgment in North Carolina. You want to estimate interest from the date the claim became due until the date of judgment.
Here is a simple illustration for North Carolina. These values are for demonstration only and should be replaced with your actual inputs.
- Principal or amount: $120,000
- Rate or cap: 12%
- Start date: 2025-01-15
- End/as-of date: 2025-09-30
Scenario
- A contractor sues a client for unpaid invoices.
- The unpaid principal is $85,000.
- The invoices became due on March 15, 2022.
- Judgment is entered on September 30, 2024.
- You want simple interest, not compounded.
- You assume a fixed annual rate of 8% for the entire period.
Note: North Carolina has specific rules and statutory rates for different types of claims and time periods. The 8% rate here is a clean, round number for illustration only. In a real matter, you’d confirm the applicable rate(s) and any accrual rules before running the math.
Input choices in DocketMath
Here’s how those assumptions map into DocketMath’s interest calculator:
| Input field | Value | Notes |
|---|---|---|
| Jurisdiction | North Carolina (US‑NC) | Lets you keep your documentation jurisdiction-aware. |
| Principal amount | $85,000 | Total amount on which interest is calculated. |
| Interest type | Simple | No interest-on-interest. |
| Annual interest rate | 8% | Fixed for the whole period in this example. |
| Start date (accrual begins) | March 15, 2022 | When interest legally starts—this is a legal question, not just math. |
| End date | September 30, 2024 | Through (and including) this date for the example. |
| Day‑count convention | Actual/365 | Uses actual days elapsed, divided by 365. |
| Compounding frequency | None | Because we chose simple interest. |
| Rounding mode | Round to nearest cent | Standard money rounding. |
If you’re documenting this for a file, you might literally paste a table like the one above into your memo or notes, then attach the DocketMath output.
Example run
We’ll walk the calculation in the same way DocketMath would present it with Explain++‑style detail.
Run the Interest 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. Count the days
From March 15, 2022 to September 30, 2024, using an Actual/365 convention and including the end date:
March 15, 2022 → March 15, 2023:
- 2022 is not a leap year
- Days = 365
March 15, 2023 → March 15, 2024:
- 2023 is not a leap year
- Days = 365
March 15, 2024 → September 30, 2024:
Break down 2024 segment:
- March 15–31, 2024: 17 days (inclusive of March 15–31)
- April 2024: 30 days
- May 2024: 31 days
- June 2024: 30 days
- July 2024: 31 days
- August 2024: 31 days
- September 1–30, 2024: 30 days
Total for 2024 segment:
17 + 30 + 31 + 30 + 31 + 31 + 30 = 200 days
Total days:
- 365 (2022–2023)
- 365 (2023–2024)
- 200 (2024 segment)
= 930 days
Pitfall: Different tools and courts can handle “inclusive vs. exclusive” end dates differently. DocketMath lets you see and document the exact day‑count logic so you can align with your jurisdiction’s practice and, if needed, adjust.
2. Convert days into fraction of a year
Using Actual/365:
[ \text{Year fraction} = \frac{930}{365} \approx 2.5479452055 ]
So the interest covers about 2.548 years.
3. Apply simple interest formula
Simple interest formula:
[ \text{Interest} = \text{Principal} \times \text{Rate} \times \text{Time} ]
Plug in:
- Principal = $85,000
- Rate = 8% = 0.08
- Time (years) ≈ 2.5479452055
[ \text{Interest} = 85{,}000 \times 0.08 \times 2.5479452055 ]
First, principal × rate:
[ 85{,}000 \times 0.08 = 6{,}800 ]
Then multiply by time:
[ 6{,}800 \times 2.5479452055 \approx 17{,}326.03 ]
Rounded to cents, the interest is approximately $17,326.03.
4. Compute total amount (principal + interest)
[ \text{Total} = 85{,}000 + 17{,}326.03 = 102{,}326.03 ]
So as of September 30, 2024, on these assumptions:
- ✅ Principal: $85,000.00
- ✅ Interest: $17,326.03
- ✅ Total: $102,326.03
5. How DocketMath would present it
If you ran this in DocketMath’s /tools/interest calculator with Explain++ style output, you’d see something like:
- A parameter summary (jurisdiction, dates, rate, day‑count)
- An explicit day‑count breakdown
- The year‑fraction calculation
- The interest formula and intermediate numbers
- A final summary table you can paste into a status email or memo
That structure is useful when you need to show your work to a partner, client, or opposing counsel.
Sensitivity check
Once you have a baseline calculation, the next step is usually: “What if something changes?” This is where DocketMath is handy—you can clone the scenario and tweak one variable at a time.
Below are three common sensitivity checks for a North Carolina interest scenario:
- Different end date (judgment delayed or accelerated)
- Different rate (e.g., statutory vs. contract)
- Different principal (partial payments or adjustments)
1. Change the end date
Keep everything the same, but move the end date three months later to December 31, 2024.
Recount the days (high level)
We already had 930 days through September 30, 2024. Now add:
- October 2024: 31 days
- November 2024: 30 days
- December 1–31, 2024: 31 days
Extra days: 31 + 30 + 31 = 92
New total:
[ 930 + 92 = 1{,}022 \text{ days} ]
Year fraction (Actual/365):
[ \frac{1{,}022}{365} \approx 2.8013698630 ]
Interest:
[ \text{Interest} = 85{,}000 \times 0.08 \times 2.8013698630 ]
- 85,000 × 0.08 = 6,800
- 6,800 × 2.8013698630 ≈ 19,049.32
So with the end date at December 31, 2024:
- Interest ≈ $19,049.32
- Total ≈ $104,049.32
Compare that to the original:
| Scenario | End date | Days | Interest | Total |
|---|---|---|---|---|
| Baseline | Sept 30, 2024 | 930 | $17,326.03 | $102,326.03 |
| Judgment 3 months later | Dec 31, 2024 | 1,022 | $19,049.32 | $104,049.32 |
The 92 extra days increase interest by about $1,723.29.
This kind of quick comparison is useful when you’re assessing the impact of a continuance or a delayed judgment date.
2. Change the interest rate
Now revert to the original dates (March 15, 2022 → September 30, 2024, 930 days), but vary the rate.
We’ll look at three rates:
- 6%
- 8% (our baseline)
- 10%
We already know the year fraction: 930 / 365 ≈ 2.5479452055.
Use the same formula:
[ \text{Interest} = 85{,}000 \times \text{Rate} \times 2.5479452055 ]
Compute:
- 6% (0.06):
- 85,000 × 0.06 = 5,100
- 5,100 × 2.5479452055 ≈ $12,992.52
- 8% (0.08):
- 85,000 × 0.08 = 6,800
- 6,800 × 2.5479452055 ≈ $17,326.03 (baseline)
- 10% (0.10):