The general rule is that you are ultimately responsible for getting medical records and filling out forms to support your Social Security Disability/SSI application. This is a very harsh rule and can result in unjust situations where Social Security makes incorrect decisions.
After filing a Social Security Disability/SSI application, Social Security will send an Adult Function Report, a Work History Report, and perhaps other forms based on the claimant's alleged disability (for example, Asthma Report, Adult Pain Report, etc.). Often Social Security caseworkers will gladly deny a case for lack of a form, despite the claimant being clearly disabled. For example, I once had a client who had a stroke and was confined to a nursing home. Social Security sent her a form to fill out multiple times when it was clear from her application that she could no longer read or write because of the stroke. They should have sent the form to her representative (me), or found her disabled without the form being completed, because she was totally incapacitated by the stroke. However, the caseworker chose to use the form as an excuse to deny her case. Luckily my client was approved at an appeal level. Moral of the story: fill out all of the forms and send them back! No matter how silly the form is, if you don't send it back Social Security will use that against you.
A claimant is responsible for furnishing medical records associated with his/her case. What?!? This is impossible for some people and disproportionately hurts the poor. Medical records can be very expensive, and some doctors won't release them to a patient. The good news is that Social Security will request the records on your behalf and pay for them. But don't be fooled! Social Security will send one request at the initial application stage, and a second request at the reconsideration stage (if your state has a reconsideration stage), but generally does not follow up on those requests. If the medical provider doesn't send the records, Social Security will not punish the medical provider, it will punish you by denying your claim.
At the hearing level, enforcement of the medical record rule becomes even harsher. Social Security will not request your medical records at all. You are responsible for getting them. The one way of getting out of this responsibility is to request a subpoena from the Administrative Law Judge to the medical provider. Some medical providers will not respond to the subpoena, however, and the Judge may make a decision with the medical records he/she already has. The good news is that most claimants have an attorney at the hearing stage, and most attorneys will request the medical records and pay for them (if the cost is not too high).
Disclaimer: This article is meant for general information only and is not intended as legal advice. Every case is different, consult an attorney if you're not sure.