woothemes/woocommerce — Issue #342: Authorize.net bug
Author: HannahHill
Created: 2011-12-08 00:03:04+00:00
State: open

I think there's a possible bug with the Authorize.net extension.

When a coupon is created for the price of a product after tax, it appears to reduce my cart to zero. However, when the customer attempts to complete the transaction, Woo asks Authorize to process it, and Authorize can't, saying it's not for a valid amount.

Genuine zero-balance transactions don't see to be an issue. When a pre-tax coupon is added for the pre-tax price of a book - reducing the cart to exactly zero, with zero tax - Woo does not ask Authorize to process the transaction. The transaction simply goes through without Authorize.

A possible theory explaining what's happening is Woo is not rounding properly when calculating taxes. A coupon for the price of the product plus tax doesn't really reduce the cart to zero; it reduces it to $0.001. So it may be that Woo is actually seeing a $0.001 balance, so it asks Authorize to process the payment. Authorize, however, can't process a payment of $0.001 (or sees it as a zero balance), and rejects it.

Note that when a coupon is made for (for example) $2.94, the $2.93 purchase goes through just fine - Woo does not involve Authorize.

So, it looks like this is a bug with the Authorize.net extension. Authorize doesn't process zero-balance transactions, but the system shouldn't ask it to.

Thanks!