How do I calculate total underpayment across multiple pay periods?

For each pay period, work out what you SHOULD have been paid (hours × correct hourly rate, including any penalty rates and allowances) and subtract what you ACTUALLY received. Add up the shortfalls across all periods, then add pre-judgment interest from each period's end date to today. This tool does the entire calculation including statutory interest and outputs a Statement of Claim PDF.

Can I claim interest on underpaid wages in Australia?

Yes. Section 547 of the Fair Work Act 2009 allows the Federal Circuit and Family Court of Australia to award pre-judgment interest on unpaid wages. The court typically calculates this at the RBA cash rate plus a margin (often 4-6%), simple interest, from the date each underpayment occurred to the date of judgment. This tool uses 10% per annum simple interest as a reasonable indicative rate.

How far back can I claim underpaid wages?

Up to 6 years from the date the underpayment occurred, under section 544 of the Fair Work Act 2009. Periods older than 6 years are statute-barred and cannot be recovered through the courts. This tool flags any period older than 6 years as a warning. The 6-year clock runs separately for each pay period — so periods within the last 6 years remain claimable even if older periods are barred.

Where do I lodge an underpayment claim?

Two main pathways: (1) The Fair Work Ombudsman (13 13 94 / fairwork.gov.au) can investigate and recover wages without you needing a lawyer — free. They are the first port of call for most workers. (2) The Federal Circuit and Family Court of Australia for formal court action (small claims jurisdiction available for claims up to $100,000). The PDF generated by this tool can be used to support either pathway.

What if my employer claims they made an honest mistake?

Honest mistake or not, the underpayment must be repaid. Civil penalties under s546 of the Fair Work Act may still apply, but courts and the Fair Work Ombudsman can take an honest mistake into account when deciding penalty amounts. Either way, you are entitled to the back-pay plus interest on the period the money was withheld.

Underpayment Claim Builder

Add up underpayment across multiple pay periods, calculate pre-judgment interest, and download a Statement of Claim PDF. The only free Australian tool that aggregates back-pay claims with interest properly modelled.

Last verified: 2 August 2026Jump to calculator ↓

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Liquid Employment Lawyers is a paid legal service and our referral partner, not free Fair Work advice. FairWork Mate may receive a referral fee from Liquid Legal. Tell them what has happened and a member of their team will call you back. For free general guidance, use our tools or call the Fair Work Ombudsman on 13 13 94.

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General information and estimates only — not legal, financial or tax advice. Always check your specific award, agreement or contract, or a qualified professional, before you rely on the result.

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