Old Navy: 20% off Coupon Code October 12, 2010 This post may contain a link to an affiliate. See my disclosure policy for more information. Now through Thursday, 10/14, Old Navy is offering up 20% off your online purchase! Just use coupon code ONBDAY20 at checkout to see the discount. **Don’t forget to go through ShopAtHome! You’ll get 4% cash back from your Old Navy purchases. Coupon code expires 10/14/10 at 11:59pm ET.