Disability Determination Services (DDS) is the state agency that makes disability determinations at the initial and reconsideration levels for Social Security disability and SSI claims.
A medical source statement is an opinion from a treating doctor regarding a patient's functional limitations. A medical source statement must be considered when determining the Residual Functional Capacity (RFC) for a Social Security disability claimant. A "medical source statement" and an "RFC" are two different things. The terms are not interchangeable.
The difference between the two terms is explained in Social Security Ruling 96-5p:
The regulations describe two distinct kinds of assessments of what an individual can do despite the presence of a severe impairment(s). The first is described in 20 CFR 404.1513(b) and (c) and 416.913(b) and (c) as a "statement about what you can still do despite your impairment(s)" made by an individual's medical source and based on that source's own medical findings. This "medical source statement" is an opinion submitted by a medical source as part of a medical report. The second category of assessments is the RFC assessment described in 20 CFR 404.1545, 404.1546, 416.945, and 416.946 which is the adjudicator's ultimate finding of "what you can still do despite your limitations." Even though the adjudicator's RFC assessment may adopt the opinions in a medical source statement, they are not the same thing: A medical source statement is evidence that is submitted to SSA by an individual's medical source reflecting the source's opinion based on his or her own knowledge, while an RFC assessment is the adjudicator's ultimate finding based on a consideration of this opinion and all the other evidence in the case record about what an individual can do despite his or her impairment(s).
I recently submitted medical source statements to DDS in support of a client's disability claim. The client has very serious chronic pain due to failed back syndrome. Her doctor gave detailed medical source statements assessing very serious functional limitations, and included his opinion that: "She is unable to stand, sit or walk, or hold concentration for more than 10 minutes at a time. There is no way she can undertake an 8-hour work day."
At Maine DDS, the reviewing physician summarized the treating doctor's medical source statements and concluded:
Statements of Social Security Disability are subject to the sequential evaluation process. Such statements and the RFCs which are used in the process are reserved to the Commissioner.
While statements on the ultimate issue of disability are reserved to the Commissioner, the DDS doctor was absolutely wrong to conclude that the treating physician's opinion regarding his patient's functional limitations is a residual functional capacity assessment. It's not. It is a medical source statement. This is a fairly basic distinction.
The DDS doctor, due to a misunderstanding of basic Social Security rules, did not adequately consider the treating doctor's opinion, or give it the deference required by 20 C.F.R. 404.1527(d)(2).
So now this claim is awaiting a hearing. However, in my view, this claim should have been granted at Reconsideration.