Health care costs and the Affordable Care Act represent the biggest concerns right now for owners of mid-sized businesses, a newly released survey shows, reported The Washington Post. In part, that may be because, now four years after the legislation was passed, most of them are still uninformed about and unprepared for the rules in the health care law.

More than two-thirds (69 percent) of mid-sized business owners say they are very or extremely concerned about the costs of health coverage and other benefits, while more than half (54 percent) say they are particularly concerned with the health law, according to an annual study conducted by the research institute at payroll firm ADP.

Some of that concern, the authors of the study note, may stem from that fact that fewer than half of mid-size businesses (firms that have been 50 and 999 employees) have put formal plans to manage the changes implemented under the health care law. Additionally, more than three-fourths of their owners say they aren’t confident that they completely understand the new rules.

On the whole, confidence among mid-size business owners is lacking. Only half of the roughly 750 respondents expect the industry in which they work to strengthen in coming year, while far fewer — 15 percent — believe the broader economy will improve.

In their report, the researchers point out that owners of mid-sized businesses often find themselves in a difficult position, in that they are “expected to operate with the agility of smaller businesses but abide by many of the same regulations that govern larger enterprises.” And perhaps nowhere is that more evident than in the health law.

Under some of most important provisions of the law, companies with more than 50 employees are considered large businesses, even though many would be considered small by other federal standards (the Small Business Administration’s definition generally includes firms with up to 500 workers). For example, they are not permitted to apply for small-business tax credits, shop for coverage on new employer insurance marketplaces or seek a small-business exemption to rules requiring companies to offer health coverage.

“A changing landscape, coupled with heightened responsibility, can take a toll on the confidence of mid-sized business owners,” the authors of the study wrote. “In 2014, they seem to be struggling to find it.”

It isn’t just health care concerns that are weighing heavily, though. More than half of respondents said they are very or extremely concerned with the number of government regulations. A third said they have been hit by unexpected fines or expenses in the past year resulting from noncompliance with government rules.

“In 2013 alone, there were more than 19,000 proposed changes to laws and regulations that impact how businesses manage employees,” Anish Rajparia, an ADP executive, said in a statement about the report. “So it comes as little surprise that the level and volume of government regulation made our list of top concerns three years running.”