When calculating freight within forwarding charges as a tax rate, you can proceed with the following steps:

1. Create a ledger in the taxes account within the Chart of Accounts. Alternatively, you can utilize the GST tax account in the taxations section for calculating the Freight charges.
2. Next, generate an Item named “Freight and Forwarding.”
3. Create a Purchase Invoice for the Supplier and include this item to compute the taxes associated with the freight. You can set the freight tax based on the Net total or Item Quantity according to the company policy.