As a general rule, only one coupon code can be entered per transaction.
However, for existing active plans, multiple discounts may be combined depending on the conditions.

• ・ For New Purchases
  Multiple coupon codes cannot be entered or combined at the same time.
• ・ For Existing Active Plans
  If a plan already has an eligible discount applied (such as a Subscription Renewal Coupon), it may be possible to add and apply another coupon (such as a Referral Discount Coupon) later.

For more details on how to use coupon codes, please refer to this page.