To redeem a promo code at CompTIA, follow these steps:

1. Visit the CompTIA Marketplace.
2. Select Certification Vouchers at top left, then pick the Basic CompTIA exam that you wish to purchase.
3. Add your items to the cart.
4. Look for the field labeled using a coupon. This field is typically located near the order summary or payment information section.
5. Enter your coupon code in the designated field and click apply. The discount should be applied to your order and the new total should reflect the savings.
6. Then select proceed to checkout. Here you will complete the checkout process by entering your payment and shipping information.

Please note that some coupon codes may have restrictions such as expiration dates, minimum purchase requirements, or limitations on certain products. Make sure to read the terms and conditions of the coupon code before using it. If you have trouble locating the restrictions, you can also contact CompTIA customer support for assistance.

The best CompTIA discount code available is 'GGL30SAVE'. This code gives customers 30% off.

CompTIA promo codes are not stackable with other discounts. According to CompTIA's policies, only one discount can be applied per transaction. This means that users cannot combine membership discounts with coupons or other promotional offers on the same purchase.