According to the U.S. Centers for Medicare & Medicaid Services (CMS) site, Coding | CMS, blanks are undesirable when reporting a POA Indicator, so the code value "1" should be used to indicate exempt from POA reporting.
Meanwhile, this practice brief released by the National Uniform Billing Committee (NUBC) (although it is dated) calls for using a code value of "1" (on electronic claims) or blank (for paper claims) to indicate exempt from POA reporting.
TR3 only provides the following:
N = No
U = Unknown
W = Not applicable
Y = Yes
When a provider bills with a POA of 1 indicating exempt from POA reporting, should this reject back, and they should bill with W for not applicable? Trying to understand the gap of information presented on POA from NUBC, CMS, and TR3.
X12 837I allowable values are N, U, W, and Y, so a 1 is not allowed to be sent on a 005010 837I claim.
Refer to the National Uniform Billing Committee (NUBC) Official UB-04 Data Specifications Manual for specifics on how to indicate a code is Exempt from POA reporting.