My employer’s formula for determining who is full time is 30 plus hours per week average over 365 days of employment. is this correct, or has it changed since obamacare?
Under ObamaCare full-time is defined as working an average of 30 hours a week or more or 130 hours a month in a measurement period between 3 and 12 months. There are a number of different measurement period types, but basically an employer would use an initial measurement period of 3 months (which coincides with the 90 day waiting period for coverage allowed by a job) and a 3 month to 12 month look-back period for determining the status of a current employee.
These shouldn't be confused with measurement periods used for determine the number of FTE (full-time equivalent employees) an employer has for the purposes of complying with the employer mandate itself.
This definition of full-time doesn't directly affect anything beyond a large employers requirement to offer coverage to full-time employees under the Affordable Care Act.
It can be a little complicated, so it's generally advised to get the assistance of a professional when determining employer responsibilities for the mandate.