QCAT Interest Calculation — How to Claim Interest on an Unpaid Debt

Two Ways Interest Can Apply to a QCAT Minor Debt Claim

When you file a minor debt application in QCAT, the principal amount — the money you're actually owed — is only part of the picture. You can also claim interest that has accrued between the date payment was due and the date of the hearing.

There are two paths. If your written contract specifies an interest rate on overdue payments (common in commercial invoices and trade credit agreements), that contractual rate applies. You'll need to attach the relevant contract clause showing the agreed rate — 10% per annum, 1.5% per month, whatever it says.

If no contractual rate was agreed, QCAT's Practice Direction 2013/09 (Interest on decisions by default for certain minor civil disputes) sets the prescribed rate you can ask QCAT to apply. This is the default for most informal debts: unpaid loans between individuals, invoices without interest clauses, or IOU arrangements.

The Daily Simple Interest Formula

QCAT uses simple interest calculated on a daily basis. The formula:

Interest = Principal × (Rate ÷ 100) × (Days ÷ 365)

So if you're owed $8,000 on an invoice that's been overdue for 200 days, and the applicable rate were 6% per annum for illustration:

$8,000 × 0.06 × (200 ÷ 365) = $263.01

You add this to your principal claim on Form 3. The interest figure needs to be itemised — state the principal, the rate, the start date (the day after payment was due), and the end date you've calculated to. The adjudicator can then verify your maths.

What Counts as the Start Date

Interest starts accruing the day after the debt became due and payable. For a standard invoice with 14-day payment terms dated 1 March, payment was due by 15 March, so interest starts on 16 March.

If your agreement doesn't specify payment terms, the date depends on when you can prove the money became owing — typically the date goods were delivered, services were completed, or a demand was made.

The six-year limitation period under the Limitation of Actions Act 1974 (Qld) still applies to the underlying debt. Interest doesn't extend or restart that clock unless the debtor made a written acknowledgment or partial payment that restarted the limitation period.

Including Interest in Your Application

On Form 3, you'll itemise:

• The principal debt (e.g. $8,000)
• Interest accrued to date (e.g. $263.01 at 6% p.a. for 200 days)
• Recoverable out-of-pocket costs (filing fee, ASIC search fees, process server fees)
• The total claimed

Keep the interest calculation running up to the date you lodge the application. At the hearing, you can ask the adjudicator to award interest through to the date of the decision — that additional accrual between filing and hearing is standard.

Attach a one-page interest calculation worksheet showing each step. A clear, verifiable calculation avoids the adjudicator having to recalculate from scratch, which speeds things along.

What If the Respondent Disputes the Rate

If you're claiming a contractual rate, attach the written clause and show how you calculated the amount. If the respondent disputes whether a rate was agreed, QCAT decides what interest to award based on the agreement and evidence.

If no rate was agreed, ask QCAT to determine interest at the rate under Practice Direction 2013/09. Keep the principal and interest amounts itemised separately on Form 3.

The QCAT Minor Civil Dispute guide includes an interest calculation worksheet that walks through the formula with your own figures, plus a deadline calendar so you know exactly when interest starts accruing for your specific situation.

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