>>..so this is the fault of the IRS and Social Security messing up - not ACA....right?

Agreed- if people have stolen SSN and the ACA systems picked it up, then the ACA has done the taxpayer a service not a disservice!

Apart from that, there's a lot of half truths around. Example:

>>The IRS has acknowledged that as a result of the administrations actions in 2012, hundreds of thousands of SSNs were assigned that shouldn't have been.

First part = true. Second part = false or at best unclear: the IRS never said the SSN shouldn't have been assigned. As you note, the amnesty mostly was a deliberate policy for people who arrived as kids, so they are no longer "illegal" and can work but not claim Obamacare or other benefits. To prevent those people accessing ACA credits the exchange required paperwork and some people didn't provide it.

The problem is that the screamers say the incomplete applications are by illegal immigrants so they must have somebody else in mind. It has to be your first group who stole or otherwise acquired a SSN illegally. KG's sentence above merges the groups to keep the heat on the ACA, but that's not credible.

My guess is that more than a few will be people who aren't supposed to access the benefits. The challenge is what to do about it if they can't repay the $ and argue that didn't understand and/or that systems should have prevented it. The moral ramifications are such that many governments procrastinate then throw it in the hardbasket and promise that it's a lot tighter now.