If your client hires you through an agency the agency (!) receives $ 80 ($100 minus the Upwork fee) and then the agency takes their cut and pays you outside of Upwork. Taxes are a different matter and the agency will have to pay US taxes and you have to pay your own country's taxes from what you are paid in your own country.
Thank you for your reply. But I still don't get it. Will be agency able to send me $ 80 ($100 minus the Upwork fee)? The reason I ask that I know that US freelancers receive payment - US taxes automatically. So that I am afraid that my US agency will be charged Upforw fee + US taxes = $ 50.
@Alena C wrote:
The reason I ask that I know that US freelancers receive payment - US taxes automatically.
No, they don't.
US freelancers receive their earnings the same as European ones. US freelancers and US agencies have to report their own taxes to the IRS.