If the whole amount of the bill recieved is VAT (f.e. the bill is issued by the broker), is there a way to book the whole amount of such invoice as INPUT VAT?

Hi there, @accounts-chern-c. 

I've got some information about how VAT works in QuickBooks Online. 

You have the option to enter directly the VAT amount of your sold items. However, you still need to select a VAT code so Quickbooks will determine the box on your VAT return to post the amount.

You can do this by creating an invoice that is exclusive of tax. Then, choose the correct VAT Code. Once done, you can now edit the subtotal amount.

Here are some good references that you can check out about handling VAT in QuickBooks: How do I set up sales GST/VAT rates and use them on forms? (International QBO).

Please let me know if there's anything else you need concerning VAT. I'll be around for you. Thank you!