I am effectively only being paid for 5 months out of this financial year due to maternity leave? The tax I pay is huge, and I want the withholding tax over these 5 months to be reduced to reflect the change in per annum income. That way I get the money now instead of waiting for the the tax refund this time next year.

Do I have to complete a variation form with the ATO, before my payroll office will reduce the tax withheld?