You need to withhold payment amounts:

• From payments you make to other workers (eg contractors)
• From payments you make to other businesses if they don't quote their ABN to you on an invoice or another document
• From payments you make to your company directors for their service to you 
• If you run your business as a company
• If you have employees
• If you pay employees from another business

If you are an employer or run a business and withhold amounts from payments, you need to:

• Register for PAYG withholding
• Determine the status of your workers (if applicable)
• Familiarise yourself with the types of payments you need to withhold amounts from
• Determine the amounts to withhold
• Report and pay withheld amounts to the ATO
• Provide the ATO with payment summaries
• Lodge an annual report once each income year has ended

MORE: See the PAYG Withholding section of the ATO website.