I would expect the social security administration to pass on information they find suspect to the IRS. That said, I have no information on how or whether agencies communicate, but isn't the whole point of sharing information to point up irregularities? I was under the impression that was why HMRC was sharing information with US authorities.
If I am not accepted under the streamlined procedure I am looking at producing 20 years of tax returns. Finding and collating the information for 3 to be done by someone else was an exercise that involved much angst. It is not an exercise I want to have to embark on. I am not clear I have sufficient records to go back that far, nor am I sure how to put the information I do have into the proper form, I will have to seek advice, and that will incur more cost. It will also be a stressful exercise, as this one has been.
The footnote by my advisor reads:
The Taxpayer is covered for social security purposes in the United Kingdom where she ordinarily resides. Self-employment tax is therefore not payable by virtue of the us/uk totalization agreement, effective from January 1, 1985. Because the taxpayer is subject to social security coverage in the United Kingdom the taxpayers is not required to pay SECA taxes in the USA.
You ask me why a certificate of coverage would be of interest to the IRS. I can go back and check my facts, but I am pretty sure that they ask for it.