News reports say that one element of an agreement to resolve the government shutdown will be a more extensive income verification process for the insurance subsidies that are a key part of the Affordable Care Act (ACA). To this point, the plan has been to rely upon "available electronic data sources" to verify income. The plan has been that Social Security would not have a role in this process. There are no details at this point on the more extensive income verification process planned for the ACA. I would guess that those states that have established their own health insurance exchanges under the ACA will be asked to do this but they may balk. More importantly, most states have not established their own health care exchanges.
If we're not going to rely just upon "available electronic data sources" to verify income and if the federal government is going to do it in most states, how will the federal government do it? It seems to me that you would need an agency that has extensive experience in income verification and which has an extensive network of field offices. It's just rank speculation on my part but that description seems to fit the Social Security Administration and no one else.