How do I make an adjustment on the BAS return for GST credit paid to customs on import? This is paid by agent and then oncharged to my client.

Hi michael189,

The amounts showing your BAS or GST reports are based on the transactions with GST code assigned on it. If you would like to make an adjustment on lodged BAS, we'll need to unlodge your BAS. There are two ways on how to unlodge a BAS: 

If you're the accountant or bookkeeper on your client's file and using QuickBooks Online Accountant, you can login on the client's file and unlodge the BAS for them.

If you are not connected to your client's QuickBooks file, your client will have to contact our Customer Success team to get the BAS unlodged.

Also, you can check on this article for your future reference: 100% GST - Importing goods. 

Let me know if you need further assistance by leaving a comment below. Have a great day!