ACA Measurement Period Calculator
For Michigan employers with variable-hour staff — restaurants, hotels, seasonal resorts, staffing and health care. Enter a few dates and see the measurement, administrative and stability periods the look-back method gives you, plus the date coverage has to be offered.
Find the dates before the hours decide for you.
The look-back method lets you measure hours over a set period, then lock each employee’s status for the stability period that follows. Pick the case that fits, change any field, and the dates update as you type.
Ongoing employees have worked a full standard measurement period. New hires use an initial measurement period that starts near their hire date.
Usually your plan year start date. Michigan small groups often renew January 1, but any month works.
The employee’s first day of work.
Starting on the first of the next month is simpler to track. The days before it count toward the 90-day administrative limit.
Anywhere from 3 to 12 consecutive months. Twelve smooths out seasonal swings best.
Time to count hours, send offers and run enrollment. Up to 90 days.
For full-time employees it must be at least six months and no shorter than the measurement period.
Include paid leave hours. We will tell you whether the average reaches 130 a month.
Your dates
Dates follow the look-back rules in Treasury Regulation 54.4980H-3. This is an estimate for planning, not legal or tax advice; confirm the method in your written plan documents.
Three places the look-back method goes wrong.
The 13-Month Ceiling
For a new hire, the initial measurement period plus the administrative period cannot run past the end of the first calendar month that begins on or after the one-year anniversary of the hire date. A 12-month measurement period with a long administrative tail breaks it, so the offer arrives late and the month counts toward a penalty.
The Gap Between Periods
The administrative period has to sit flush between the measurement period and the stability period. A gap of even a few days means an employee is neither measured nor locked, and that is the month the IRS asks about on the 1095-C.
Hours You Forgot to Count
Paid sick time counts as hours of service. Under Michigan’s Earned Sick Time Act most employers now provide it, so an employee averaging 126 worked hours can cross 130 once paid leave is added in.
The Michigan employers who need this most.
The look-back method only earns its paperwork when hours swing. If your schedules are fixed, monthly measurement is simpler and nobody needs a stability period.
Restaurants and Hospitality
Shift counts move with the season and the staff turns over fast. A 12-month measurement period stops a busy summer from making a server full-time for the whole next year.
Seasonal and Resort Employers
Northern Michigan resorts, golf courses and marinas hire for a season. The seasonal-employee rules let you measure new seasonal hires over an initial period instead of offering coverage from their first day.
Health Care and Staffing
PRN and per-diem staff can average 28 hours one quarter and 38 the next. The method is what lets you decide once a year instead of every month.
Employers Near Fifty
If you are approaching 50 full-time-equivalent employees, choose a method before you cross, not after. Without one, you are measuring month by month in the year the mandate first applies.
Test whether the offer is affordable → Estimate the penalty if it is missed →
What employers ask about measurement periods.
Who counts as full-time under the ACA?
An employee who averages at least 30 hours of service a week, which the IRS treats as 130 hours in a calendar month. Hours of service include paid time off, not just hours worked.
Do I have to use the look-back method?
No. You can measure each month on its own. The look-back method is optional, and it helps most when hours vary. If you use it, describe it in your plan documents and apply it the same way to everyone in a category.
Can part-time and full-time staff have different periods?
Yes, within limits. Periods can differ between salaried and hourly staff, between employees in different states, and between bargaining and non-bargaining groups. They cannot be set employee by employee.
What happens if I miss the offer date?
Any month a full-time employee goes without an offer can count toward the employer mandate penalty if they buy marketplace coverage with a subsidy. The penalty calculator shows what that could cost for 2026 and 2027.
Send us your renewal.
We’ll tell you whether it looks competitive, where we see opportunity, and the five questions we’d put to your carrier. No cost, and no obligation to move anything.
The renewal letter
Your current plan summary
Contribution split by tier
Enrolled counts by tier
Four documents — two more if your group is 50 or more. Nothing else; every extra one is a reason to postpone.
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