Over time, Commonwealth reported, employment patterns might change, leading to fewer firm sizes and work schedules near the thresholds, potentially affecting up to 0.5 percent of the workforce.

Most employers subject to the mandate already comply with it. Among those employers that don't, most are likely to find compliance to be less expensive than avoidance, explains study author Sherry Glied from New York University.

Beginning this January—under the mandate's latest delay—firms with 100 or more full-time employees will be required to offer affordable health insurance coverage to employees who work more than 30 hours a week or face possible penalties. Firms with 50 to 99 employees have until January 2016 to comply.

Many have warned the employer mandate would cause a massive surge in part-time workers as employers would cut employee hours to dodge the mandate. But other studies, such as that by the Urban Institute and the University of Illinois last month, echo the Commonwealth's major findings: That PPACA, at least so far, hasn't increased the number of part-time workers.

The employer mandate has been under even more scrutiny this year. Originally scheduled to go into effect this year, the mandate has been delayed twice by the administration, which says it needs more time to implement the provision.

Attention to the mandate hit a new high at the Benefits Selling Expo back in April, when Robert Gibbs predicted during a keynote address that the mandate would never be put into effect.

"I don't think the employer mandate will go into effect. It's a small part of the law. I think it will be one of the first things to go," he said to a notably surprised audience.

Gibbs, a former longtime advisor to President Barack Obama, noted there aren't many employers who fall into the mandate window. He said the delays point to the fact that the mandate "will never happen."