Envato is required by law to withhold certain taxes from your earnings as an author. The relevant section of the author agreement says:
21. If required by law, we may deduct or withhold taxes (including withholding tax) in connection with your being an author. If so, we will give you relevant document that’s required by law about the deduction or withholding (like documentation allowing you to access rebates or credits, or to manage your tax affairs).
As an Australian company, Envato Elements Pty Ltd is required to withhold Australian Royalty Withholding Tax (AU RWT) from earnings paid out to authors located in other countries. The tax rate that applies can vary between 0% and 30%, depending on the tax treaty (if any) between Australia and your country.
We use the country information from your tax form (W8/W9) to calculate the amount to withhold. So please make sure you keep this information up to date if you move countries.
If taxes are withheld from your earnings, we will provide you with a relevant document each year to help you manage your tax affairs, for example to claim a credit on your tax return for the amount withheld.