(1) If you're asking what size employer has to offer a qualifying employer-sponsored plan to its full-time employees (or, likely, be subject to a penalty for not doing so), then it's employers with 50 or more full-time equivalent employees. The number of full-time employees is added to the number of hours worked by non full-time employees divided by 120 (per month). If the result is 50 or more, the employer has to make coverage available to the full-time employees. It gets a little more complicated when we try to figure out what portion (if any) of that coverage the employer has to pay for itself in order to avoid penalties. That depends a great deal on the employer's circumstances (e.g. the household income of respective employees).
(2) I assume you're asking what the penalty is for not maintaining the required coverage - i.e., not getting or being able to get it through work and not getting it any other way (through, e.g., an exchange, Medicare, or Medicaid)? Calculating the penalty is a tad bit complicated, but here are the basics:
(a) It's the
greater of:
(i) 2.5% of their household income after taking out their exemption and standard deduction (the percentage is phased in - it's 1% for tax year 2014, 2% for tax year 2015, and 2.5% for later tax years); and
(ii) $695 times the number of people (e.g. the taxpayer, a spouse, dependents) that didn't have the required coverage with the maximum multiplier being 3 (the $695 is also phased in - it's $95 for tax year 2014, $325 for tax year 2015, $695 for tax year 2016, and $695 COLA-ed after that). The dollar amount that is used is cut in half (e.g. $347.50 instead of $695) with regard to people under the age of 18, but the total penalty can still be 3 times the full dollar amount (e.g. $695).
(b) The penalty is prorated by the month. Generally speaking, they pay it for months during the given year in which they don't have the required coverage - not necessarily for the entire year. They get one 'free' period per year, of up to 3 months without the required coverage, for which they wouldn't have to pay a penalty. But if a period is longer than 3 months, they have to pay the penalty for all of it.
(c) The total penalty for a year is capped at the nationwide average cost of plans that would have provided them with the minimum required coverage, taking into account their family size (i.e. suitable "bronze level" coverage plans).
(d) The don't have to pay a penalty if they don't make enough to have to file an income tax return.
(e) They don't have to pay a penalty if the amount they would have to pay for the required coverage, through their employer if such coverage is available or through an exchange if it is not (i.e. after taking into account what their employer might pay in the former case or the federal subsidy they might qualify for in the latter case), is more than 8% of their household income. That 8% also gets indexed, but I won't go into how.
(f) There are other exceptions, e.g. the recognized religious sect exemption, for individuals not lawfully present, for people determined to have had an applicable hardship.
(3) For most people, it will be in 2015 when they file their return for the 2014 tax year.
