Is there a requirement for employers to track the number of FT and PT employees so that they can comply with having 50+ employees.
Under ObamaCare, Employers count full-time equivalent hours (part-time, full-time, seasonal, etc). If the average is over 50 they must provide coverage.
In order to get that average an employer would count full-time employees and then use a reasonable method for crediting part-time hours.
Learn more about Employer Shared Responsibility.