As the guardian, it is precisely your responsibility to decide what is best for the child, and make decisions on their behalf. That's what being a parent (or, more precisely, guardian) is.
What happens when a form at the doctor's office requires it?
Sounds like a doctor's office is running a scam.
it should be with their insurance, which is yours, and unless the doctors office is planning to come after them for debt collections they don't need it, in which case would be pretty wild since you are their guardian; ergo fiscally responsible for them.
nah, SSN is only for tax returns and that is just to claim them as a dependent. I kinda feel bad every year for even doing that.
Huh?
Even for traditional married two-parent families, the parents can and do have different insurance than their kids. (For example, my husband's employer won't allow me to be on a plan with him, so we are needing to choose between all of us on my higher cost plan, or he & the baby on his high deductible plan. Odds are, I'll be taking the baby in to many appointments by myself - and we are likely to have different insurances.)
Also, insurance bills/codes based on the patient that they see. If they see the kid, they are billing the insurance based on the kid not the parent. This is likely why they request the SSN, for coding & identification, rather than for debt collections.
The only places that should be requesting an SSN are the SSA, the IRS, the State department when ordering a passport, banks when opening an account (because they have to report to the IRS) and health insurance companies, Medicaid, and healthcare.gov (because they have to report to the IRS). That's it. If anyone else asks they are either ignorant or running a scam. A doctor's office should just be asking for insurance information because they can just call the insurance company to verify your coverage.
You assume everyone has insurance.
They want it so they can send debt collectors after you if you don't pay.
I'd think they'd want it even if you had insurance, for if it's not covered, or if you didn't pay certain deductibles or copays or something.
EDIT: Missed the next page. Yep. That form. Then they'd want your SSN to record the debt. How do you think so many people have medical debt on their credit report? Clearly they had to give their SSN at some point.
Which could include their child's SSN. For a responsible parent, this shouldn't be a problem for the child. For a non-responsible parent, the child has many other problems, this is a relatively minor one (great pun, arebelspy!).