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Child support liability calculator (before 31 March 2015)

About this calculator

This calculator is used to work out child support liabilities up to and including 31 March 2015.

Use of this tool does not result in data being submitted to us.

When to use this calculator

Use this calculator as a guideline only, based on the taxable income you enter and the child support formula assessment.

For child support assessments after 31 March 2015 use our Child support - liability/entitlement calculator.

What you will need
  • Your total income for the previous year or two years if you're an IR3 filer or live overseas.
  • The number of children you were paying for.
  • The number of children you had in your care. 
  • Whether or not you had a partner.
After you finish

The calculation is a guideline only, based on the details you provided.

This does not take into account estimations of income, multiple shared custody, split custody, or other special circumstances.

If you think your calculation differs from what we sent you in your assessment letter, please contact us to discuss your assessment.


No information you provide while using the calculator is recorded, saved or in any way referenced by Inland Revenue. The calculator is stored on a secure part of our website to prevent unauthorised interception. If you are unable to access the calculator, you may need to update your browser and/or firewall settings.