Nursing homes with visiting physicians or providers would do well to uncover their troubled histories with Medicaid or Medicare programs in other states or face billing nightmares, and worse, federal scrutiny.

A newspaper investigation has revealed that practitioners often go undetected as practitioners in one state after being involved with or kicked out of programs in another state.

Reuters found that more than one in five of the thousands of doctors and other healthcare providers in the U.S. prohibited from billing Medicare are still able to bill state Medicaid programs – a violation of the Affordable Care Act provision that requires states to suspend the billing privileges of most providers who have been “terminated” or “revoked” by another state or Medicare, Reuters reported.

The news organization exposed about 1,800 providers who had slipped under the radar. After reviewing the list, 32 states and the District of Columbia supplied data showing they paid at least $79 million to 269 of the providers after their terminations elsewhere. Reuters said possibly “hundreds of millions” of such claims have likely been made since so much of it goes unnoticed because of inadequate state and federal data.