Depending on your organization, you may have access to the Apple Employee Purchase Program. In order to see if this program is available to you, click here.
If you are eligible to use the Apple Employee Purchase Program, you can click the "Shop Now" button on the offer page to get to the designated Apple website where all discounted pricing will automatically appear. Employees can purchase or sponsor up to 3 computer systems, 3 iPad, 3 iPhone, 3 Watches and 10 iPod devices per calendar year, as well as software and peripherals.
Since all discounted pricing already appears on the Apple EPP website, there are no promo codes required.
Additionally, you can call Apple at 877-377-6362 to make your purchase. You'll want to ensure that you request your Employee Purchase Program preferred pricing when you call.
Keep in mind that the discount is for select items and the newest product releases may not be discounted until several weeks after the product is available.