Are you an employer? Are you aware of the recent changes?
As of October 1st 2016 the ATO have put out changes to the PAYG withholding tax rate for employees earning over $80,000 a year.
If any extra tax was withheld from your employees before the rate change on October 1st, your employees will be credited when they lodge their 2016-17 income tax returns. No employer adjustment or refund is required.