Maybe you have an IRS "secret shopper" testing your knowledge of the law.

https://www.law.cornell.edu/uscode/text/26/24

IRC 24(e)(1):

"No credit shall be allowed under this section to a taxpayer with respect to any qualifying child unless the taxpayer includes the name and taxpayer identification number of such qualifying child on the return of tax for the taxable year and such taxpayer identification number was issued on or before the due date for filing such return."

Rick