Box 12 code Z

Hello,

Why am I getting a message that the above code is income under a nonqualified deferred compensation plan that fails to satisfy section 409A.  This is unusual and the calculations for the additional tax and interest on this are not supported.  This has been on my W2 for many years and I have not had this pop up as an error on my tax return on turbo tax.  Why is it popping up now?  If Turbo Tax does not support this, where do you suggest I get expert advice for handling this?