If you don't give your employer your TFN or ABN they will withhold tax from you, in relation to the discount on your ESS interests.
If withholding tax applies, your employer must remit (pay) the tax to us – the rate of withholding tax is the highest individual tax rate plus the Medicare levy (and for the 2015–2017 income years, the Temporary Budget Repair levy).
Your employer can recover this amount by offsetting the withholding tax paid against any other amounts owed to you, such as salary and wages.
You can also claim a credit for the amount of withholding tax paid on your tax return. The total amount of withholding tax paid for which you can claim a credit will appear on your ESS statement.
Remember, this won't apply to you if you have already given your employer a TFN declaration.
Your employer must withhold tax if they don’t have your TFN or ABN.