CMS-1500 · Box 9

Other insured (when secondary coverage exists).

What goes here

Box 9 = other insured's name. 9a = policy or group number. 9b = DOB + sex. 9c = employer or school. 9d = the other plan / program name.

Common mistakes

The whole 9-cluster is left blank when coordination of benefits actually applies. 9c and 9d swapped — payer field order is strict on the 02/12 form.