I get health insurance through work. What should I do to get ready for the new health care law?

Not much. If you get health insurance through your work or someone else's, as almost half of Americans do, you will likely notice little if any change in how you get health care. The only thing you'll ready need to do is to hang onto a couple of forms that you'll be given:

• By Oct. 1, 2013, your employer will give you a form with the catchy name "New Health Insurance Marketplace Coverage Options and Your Health Coverage," or something similar. Don't throw the form away.
• At some point in early 2015, your insurer will send you a form (the government hasn't specified what it will look like) verifying that you have insurance. You'll need to submit that when you file your 2014 tax return.

Even if you have insurance through your employer, you might need to consider other options in two scenarios:

Your employer cancels your plan for 2014

That could happen, especially if you have a so-called "mini-med" plan that provides severely limited benefits. Those plans had an exemption to continue operating through the end of 2013 only. If you lose your employee coverage, you may be able to get better insurance through your state marketplace and possibly qualify for subsidies to help pay for it.

You have a very expensive plan

In that case, you may—or may not—qualify for some financial relief.

Dig out that employee form you got in the fall. You should find what your employer charges employees for the cheapest individual plan it offers.

If that number is more than 9.5 percent of your household income, and your income is below certain levels, you can turn the plan down and purchase your own coverage on your state's marketplace, with a subsidy. But if it's less than 9.5 percent you can get a subsidy only if your plan covers less than a "minimum value" of expected medical costs. The form should include information about that.

But an important catch may ensnare some families with multiple members covered on the same plan.

If, for example, your employer charges you $20 a month but $750 more to add your spouse and $250 more to add your kids, even if the total premium adds up to more than 9.5 percent of your family's income, you can't get a marketplace subsidy because the employee-­only contribution is the one that counts. It's unfair and may need to be fixed with new legislation.

If that happens to you, price plans in the marketplace for your dependents anyway. Even at full price it might be cheaper than keeping them on your employer plan.

—Nancy Metcalf