Create a credit class when you want credit that can only be spent on certain things, such as shipping dollars that can only be spent on shipping.
Before you start
Decide what the credit class's credit should be spendable on. If you want credit that can be spent on anything, you can use the Everything credit class instead of creating a new one. See What is a credit class?.
Steps
Go to Settings > Loyalty & Credit.
In the Credit Classes section, select Add Credit Class. A new row appears.
In Name, enter a name that describes what the credit is for, for example Shipping Dollars.
All the options start ticked: Wine, Cider, Beer, Spirits, Other products, Shipping, Club runs, Gift cards and Excluded products. Untick everything the credit should not be spent on. For shipping dollars, untick everything except Shipping.
Select Save.
What happens next
The new credit class appears in the Credit Classes table, with its Eligibility showing what its credit can be spent on. You can now choose the credit class when you set up your loyalty program or give a customer manual credit.
Troubleshooting
A customer can't spend their credit on a product. Check that the product's type (for example Wine) is ticked in the credit class. If the product is on your Excluded products list, the credit class also needs Excluded products ticked. See How to stop credit being earned or spent on certain products.