We export goods on payment if IGST.
Now, when we enter the shipping bill details in Zoho Books, it debits the Input IGST account by default without any option to change this accounting behaviour which I think is not right because this amount is not claimed as input tax credit. Rather it is refunded by the customs authorities after the GSTR-1 and GSTR-3B returns are filed for the concerned tax period.
A separate ledger preferablly named "IGST Paid on Exports" under "Current Assets" should be credited along with a reference number to track the bills against which refund has not yet been received.