While most experts will advise undocumented aliens in the United States not to mess with Uncle Sam but it is way too tempting not to get all the freebies. That is why there is so much fraud committed by illegal immigrants with their taxes and taking advantages of loopholes to get benefits from government programs reserved exclusively for US citizens and legal residents. It is even easier to do if the illegal alien has stolen the identity of a citizen using fake papers. Since there are private contractors involved in the programs (they have all the incentives to have as many people take advantage of the program as possible so that they can then bill Uncle Sam) it is easy to enroll in programs like Medicare.
What will happen if the Government wants to track you down? So a lot of people write asking if they will ever be caught for this theft that has gone on for decades. You see while the Government is too broken to find the culprits, typically Medicare will try to match the information in the databases maintained by Social Security Administration (SSA) and Department of Homeland Security (DHS). Information is not publicly available on what other databases are accessed but it is possible for the staff at Medicare to nail down the immigration status of an individual fairly accurately, even if you have been working illegally and paying taxes not only through FICA withholding at work but also by filing a return each year (merely paying taxes does not entitle illegal aliens to get this benefit and the Government treats this crime as fraud). It is also important to remember that if you ever plan to legalize your status this paper trail will come to haunt you. In other words, if you are illegally in the US and have been taking advantage of Medicare, it is a good idea to hire an attorney immediately to find out what your chances of being caught are. Also do not file any application to USCIS without a lawyer because this record of theft in government databases might not only make you ineligible for adjustment of status, you maybe charged with a crime.