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Interest Calculator

This tool helps calculate interest on late progress payments under a construction contract in Queensland, pursuant to the Building Industry Fairness (Security of Payment) Act 2017 (Qld) (BIF Act).

Interest is payable on late progress payments under section 73 of the BIF Act.

Building Industry Fairness (Security of Payment) Act 2017 (Qld) – section 73

73 Due date for payment

  • (1) A progress payment under a construction contract becomes payable—
    • (a) if the contract provides for the matter—on the day on which the payment becomes payable under the contract; or
    • (b) if the contract does not provide for the matter—on the day that is 10 business days after the day a payment claim for the progress payment is made under part 3.
  • (2) Interest for a construction contract is payable on the unpaid amount of a progress payment that has become payable at the greater of the following rates—
    • (a) the rate stated in the contract;
    • (b) the rate prescribed under the Civil Proceedings Act 2011, section 59(3) for a money order debt.
  • (3) However, for a construction contract to which the Queensland Building and Construction Commission Act 1991, section 67P applies because it is a building contract, interest is payable at the penalty rate under that section.

As per section 73(3) of the BIF Act, the penalty interest rate under section 67P of the Queensland Building and Construction Commission Act 1991 (QBCC Act) may apply. That section provides:

Queensland Building and Construction Commission Act 1991 (Qld) – section 67P

67P Late progress payments

  • (1) This section applies if—
    • (a) the contracting party for a building contract is required to pay an amount (the progress amount) to the contracted party for the building contract; and
    • (b) the progress amount is payable as the whole or a part of a progress payment; and
    • (c) the time (the payment time) by which the progress amount is required to be paid has passed, and the progress amount, or a part of the progress amount, has not been paid.
  • (2) For the period for which the progress amount, or the part of the progress amount, is still unpaid after the payment time, the contracting party is also required to pay the contracted party interest at the penalty rate, as applying from time to time, for each day the amount is unpaid.
  • (3) In this section— penalty rate means—
    • (a) the rate made up of the sum of the following—
      • (i) 10% a year;
      • (ii) the rate comprising the annual rate, as published from time to time by the Reserve Bank of Australia, for 90 day bills; or
    • (b) if the building contract provides for a higher rate of interest than the rate worked out under paragraph (a)—the higher rate.

Calculating the QBCC Act penalty rate requires the 90-day Bank Bill Swap Rate (BBSW), which is published daily by the Reserve Bank of Australia. Our calculator automatically fetches the latest official RBA statistics every day. By using the calculator, you acknowledge and agree to our disclaimer below.

Calculate simple interest based on an interest rate specified in your contract.

Calculate interest at the penalty rate under section 67P of the Queensland Building and Construction Commission Act 1991 (Qld) (QBCC Act). This rate is 10% plus the 90-day Bank Bill Swap Rate (BBSW), which is updated daily.

Disclaimer

This interest calculator is provided as a guide only and should not be relied upon as a substitute for professional legal or financial advice. The calculations are based on the inputs you provide and, for the QBCC Act rate, on publicly available data from the Reserve Bank of Australia which we endeavour to update daily.

While we strive for accuracy, Sopal provides no warranty and accepts no liability for any loss or damage arising from the use of this calculator. Users should independently verify all calculations and, where applicable, the underlying RBA rates, before inclusion in any formal submission or legal document.