> the letter you received from the IRS
this is presumably not the same as "the link to Letter 6416"
this is presumably not the same as "the link to Letter 6416"
https://www.irs.gov/credits-deductions/2021-child-tax-credit...
To me it reads like Letter 6416 is meant to add specificity to "the letter" in the previous sentence.
EDIT: I've found other examples of Letter 6416 online on non-IRS websites that do have a phone number at the upper right. I'm not sure if the phone number's absence from the sample PDF on the IRS website means it has been removed, or if non-sample copies would have a phone number.