Discover is the only card issuer we have checked whose own page invites you to share your referral link on social media.
What the page says
Discover's referral page tells you to text, email, or share your personal link on social media. That is an affirmative instruction rather than an absence of a rule, which makes it different in kind from the issuers whose terms simply never mention where you may post.
What Discover restricts instead
The constraint sits on how the referred person applies, not on how you share. They must apply online through the digital link you sent. Discover states that phone, mail-in, and other digital applications are not eligible, so a referral that arrives through any other channel does not pay.
What Discover does not publish
The referral amount and the annual cap are disclosed only inside your account. Figures quoted on comparison sites are not Discover's own, and we do not repeat them. Discover also says statement credits may be taxable without naming a form. Note that the 1099-MISC language people cite belongs to Discover's student loan referral, a different product on a different site.