If you have received a 20 percent off coupon, it may be possible to use it online. Whether the coupon arrived in your inbox or by mail, read it carefully in its entirety to determine what the terms are and if it's applicable towards online purchases.
Along with specifying when it expires, the coupon will likely indicate whether it's valid for in-store or online purchases or both. A code may be provided. When making your online purchase, type this code when prompted before checking out. An "invalid code" message or the absence of a discount likely mean that you cannot use your coupon online.