When shipping internationally with DHL, you may incur duty charges. By default, Shiptheory will ask DHL to make the shipment recipient response for any duty charges, where possible.

I Want to Pay my own Duty Charges

From the advanced section of the DHL edit page in Shiptheory is a field that you can enter your Duty Account Number. 

You will also need to set the duty payee to The Recipient at the Select the Duty Payee menu, shown below.

Entering a value into these fields will make you responsible for any duty charges incurred.