At what point would two merging companies that had fewer than 50 employees last year fall under the ACA’s employer mandate and reporting requirements?

The ACA's employer mandate applies in the current year if an employer (or two companies that are commonly owned) has 50 or more full time employees (including equivalents) in the prior calendar year. Importantly, in counting “employees” the employer needs to calculate full-time equivalents, which include both full time (FT) employees (those working 30 or more hours per week) and part-time (PT) employees (for anyone who is not FT, add the total number of PT employee hours per month and divide by 120).

Also, only employees are included in the count, so owners would only be included in certain situations. For example, if owners are partners in a partnership, S-corp shareholders of more than 2%, or LLC owners where the LLC is taxed as a partnership, they would be considered “self-employed” and therefore wouldn't be included. If they were C-corp owners/employees (received W2 income) or LLC owners where the LLC is taxed as a C-corp and have owner/employee status (received W2 income), then they'd be considered employees and would be included in the count.

The ACA employer mandate count looks at the average number of employees working during the previous calendar year. The count also pulls in commonly-owned companies together, so that employees of both companies are included.

So, if two companies under common ownership hit 50 FT equivalents in 2019, then the mandate would apply in 2020. Assuming the two companies didn't have 50 employees/equivalents in 2018, they wouldn't have to comply with the mandate in 2019. Instead, they'd have to comply with the mandate in 2020. They would actually have until April 1, 2020 (there's a special rule that allows them a three-month “grace period” the first year that they're subject to the mandate).

That said, it might be easier to just comply beginning January 2020 (particularly if they have a calendar year plan). So 2020 would be the year that they'd have to identify and offer affordable coverage to all their FT employees (those working 30 hours or more per week); part-timers would not have to be offered coverage.

As for reporting, that attaches to the employer mandate's application. So if the mandate applies in 2020, the employer would have to report in 2021.The employer group would have to file Forms 1094-C and 1095-C (for each FT employee) with the IRS in early 2021 (by February 28 if filing by paper and by March 31 if filing electronically); and they would also have to distribute a copy of 1095-C to each FT employee by January 31, 2021. The IRS could potentially delay those due dates (they've done that in years' past), but those are the general deadlines.