Tax treatment of stipends to corporate board members

If by "stipends" you mean Director's fees, then the taxation depends on whether they are also employees or not.

• non-employee directors receiving director's fees report them as self-employment income.
• employee's who are also directors receiving director's fees should have them included with their wages subject to FICA and Medicare taxes.
  

I think Corporate employment is definitely one test for self-employment tax applicability.  But I question the applicability if you're talking about somebody's G'ma that is in the Board meeting just to enrich the appearance of the Board and does not possess any professional status beyond best cookie baker in Hoboken.  If there's no "service"  (speeches, consulting, press conferences, other representation of or on behalf of the Corporate Entity) then how can G'ma's knitting constitute employment?  I'm suggesting there's an argument beyond getting a W2 from the Corp but only if no W2 exists.