Hu-Nam-Nam v New York Cent. Mut. Fire Ins. Co., 2016 NY Slip Op 26237 (App. Term 2d Dept. 2016)
A billing provider seeking to recover no-fault benefits for services rendered to an assignor must provide, at the bottom of the claim form, a taxpayer identification number either in the form of a social security number or an employer identification number. Social security numbers are used to identify individual persons, while employer identification numbers are used to identify employers (see 26 CFR 301.6109-1 [a]  [ii]). “An individual … who is an employer or who is engaged in a trade or business as a sole proprietor should use an employer identification number” (26 CFR 301.6109-1 [a]  [ii] [b]), since an employer identification number is required if the taxpayer “[p]ay[s] wages to one or more employees” (IRS Publication No. 334 [Tax Guide for Small Business]). Thus, it is permissible for a billing provider operating as a sole proprietor to use his or her own social security number on the claim form if it is the billing provider who rendered the services in question. However, where, as here, a doctor bills for services rendered by a treating provider in that doctor’s employ, it is impermissible for the doctor to bill using his or her own social security number.
Nothing better than putting your social security number on documents to be distributed to the world. That is the vehicle for classic fraud. Legally, this is the type of “technical issue” that the Court of Appeals warned against in Malella. Yet, this is not a Malella defense since and is deemed an improper billing defense. The Court held as follows: “As defendant demonstrated that the claim form submitted by plaintiff was for services performed by plaintiff’s employee, that the claim form was submitted under plaintiff’s social security number, and that the denial of claim form based upon improper billing was mailed within 30 days of defendant’s receipt of the claim form, defendant established its entitlement to summary judgment.”
I am not sold this is a defense, but you do not have to sell me on it. I am not the court.