It has the employer fingerprints all over it, and I lived in Illinois long enough to know how local government works.  There is no VEBA fairy, that waved a magic wand and brought together all the employees with no involvement of the boss.  You're the one who started out wanting to pay Medicare tax, and then others chimed in with Trick The Computer advice.  I know the NEC for a large amount -- it must be at least $25,000, if you're saying the Medicare tax is around $400 -- will generate a CP 2000 asking for SE tax.  My solution is the 4852, but it's your client.  Let us know in a couple years what worked.