I wish to reduce supplier invoice amount by creating an expense with the reduction created.

I know a way how to handle that, Miriam162.

You can the fee for the transportation/shipping fee as a vendor credit and then apply it to the bill. This way, you'll be able to reduce the total amount. Here's how:

1. Click the + New button.
2. Choose Vendor credit.
3. In the Vendor drop-down menu, select the appropriate vendor.
4. Enter the category, product, or service you’re getting credit for.
5. Hit Save and close.

When you’re ready to apply the credit, here’s how to do it:

1. Click the + New button.
2. Choose Pay bills.
3. Select a bill for your vendor from the list. You'll see the available credit with this vendor in the Credit Applied field.
4. Complete the rest of the fields like you normally do.

I'm also adding this article to learn how to track all money you've paid to a vendor for a particular date range: Run a report with vendor totals.

Just tag me in the comment section if you need more help in recording your other business transactions. Have a productive week ahead.