Congratulations on obtaining your judgement! Now it’s time to open a bottle of champagne and grab your calculator. We’ll walk you through the process of calculating post-judgement interest with partial payment. Let’s go!


Step 1: Determine the Judgement Amount and Judgement Date

Post-Judgement Interest starts accruing automatically based on the amount owed or awarded under the judgement, beginning from the date on the order.


Step 2: Secure the Applicable Interest Rate

The interest rate may be set by the contract between the parties or by Courts of Justice Act, R.S.O 1990 c. C43. You can find the applicable interest rate by looking up the quarter when the judgement was issued through the table here, published by the Ontario Ministry of the Attorney General.


Step 3: Calculation

Let’s consider an example to demonstrate the calculation:

E.g.: The judgement was awarded to the creditor for $100,000.00 on February 1, 2023. The debtor made a partial payment of $50,000 on April 30, 2023 and is scheduled to pay the remaining balance on September 15, 2023. We need to calculate the amount due on the final payment date.


Step 3.1: Calculate Interest Period Days

First, determine the number of days for each interest period:


Period A: Judgement Date to First Payment Date

30-Apr-2023 to 01-Feb-2023 = 88 days


Period B: First Payment Date to Final Payment Date

15-Sep-2023 to 30-Apr-2023 = 138 days


Step 3.2: Calculate Post-Judgement Interest Per Diem

(Judgement Amount x Interest Rate % ) ÷ 365* = Post-Judgement Interest Per Diem

**If it is a leap year, use 366.

In the example, the interest rate in the first quarter of 2023 is 5.00, according to the table published by the Ministry of the Attorney General. We need to calculate two different interest per diem amounts as the interest must be calculated on the unpaid amount only.

For period A, the interest per diem = $100,000 x 5% ÷ 365 = $13.70

For Period B, the interest per diem = ($100,000 – $50,000) x 5% ÷ 365 = $6.85


Step 3.3: Calculate Total Post-Judgment Interest

Post-Judgement Interest Per Diem x Number of Days = Post-Judgement Interest

In this example, we need to calculate the post-judgement interest for both before and after the first payment date on April 30.

Post-judgement interest before the first payment date (Period A) = $13.70 x 88 days = $1,205.48

Post-judgement interest after the first payment date (Period B) = $6.85 x 138 days = $945.21


Period A Interest + Period B Interest = Total Post-Judgement Interest



Step 3.4: Calculate Total Outstanding Balance

To calculate the total outstanding balance on the final payment date (September 15, 2023):

Total Post-Judgement Interest + Unpaid Judgement Amount = Total Outstanding Balance

$2,150.69 + ($100,000 – $50,000) = $52,150.69



Calculating post-judgement interest with partial payment may require some math, but with a few calculations, you can determine the total outstanding balance accurately. You may need to consult legal professionals or use specialized software to ensure compliance with specific jurisdictional rules.


Jennifer Jiang


Nothing contained in this post constitutes legal advice or establishes a solicitor-client relationship. If you have any questions regarding your legal rights or legal obligations, you should consult a lawyer.