May 15, the deadline for getting Medicare drug coverage (Part D) this year, is fast approaching. If you're still wondering whether to sign up, these are important questions consider:

Will the enrollment period be extended beyond May 15?

Only if the law is changed. Some in Congress have raised the question, but President Bush, many lawmakers and the health insurance industry oppose a change. The following assumes that the May 15 deadline will remain.

Is it true the late penalty may be waived just for this year?

Several members of Congress have proposed changing the law so that people who fail to sign up by May 15 but do so in the next enrollment period (Nov.15-Dec.31 2006) will not pay a late penalty (see below) in 2007. Although this idea may gain traction before the November mid-term elections, it's unlikely the law will be changed before May 15 and may not be changed at all. So failing to enroll by May 15 on this basis would be a gamble.

When is the latest I can sign up?

Enrollments made online at medicare.gov must be received must be received before midnight Pacific Time on May 15-or by midnight in your own time zone if you sign up by phone to the Medicare hotline at (800) 633-4227. Enrollments faxed or phoned to a Medicare drug plan must arrive at the plan's office before midnight in the time zone where it is located. Enrollments mailed to a plan will be accepted if postmarked on or before May 15.

However, a last-minute rush of enrollments may tie up phone lines and make it difficult to get through on time. If you want Medicare drug coverage this year, don't wait till the last day to sign up.

What happens if I don't sign up by May 15?

If you're already a Medicare beneficiary and have no comparable drug coverage from elsewhere, two things will happen: You will not be able to get Medicare drug coverage for the rest of 2006. (Your next chance to sign up will be from Nov. 15 to Dec. 31 for coverage in 2007.) And you will face a penalty in the form of higher premiums once you do enroll.

However, if you already have drug coverage from elsewhere (such as an employer or union, Veterans Affairs or TriCare) that is at least as good as Medicare's, you need not sign up now. Nor will you be penalized if you lose (or drop) that coverage at some future date-provided that you enroll in a Medicare plan within 63 days of its ending.

What does the "late penalty" really mean?

It is a penalty for signing up later than the enrollment period in which you first become eligible for Part D. An extra payment, based on how many months you delayed, will be added to all future premiums and will increase each year. Over time, you will pay a lot more for the same drug coverage than if you'd signed up on time. [See chart.]

The penalty is 1 percent of each year's national average monthly premium (NAP) multiplied by every month you are without coverage. Here's how that formula works in practice, if you're a Medicare beneficiary now:

• If you miss the May 15 deadline, you won't be able to sign up till the end of 2006, and you'd have seven months (June 1 to Dec. 31, 2006) without coverage. So in 2007, on top of your premiums, you'd pay 1 percent of the 2007 monthly NAP x 7 (months without coverage). Multiply that by 12 for the total penalty over the whole year. For example, if the 2007 monthly NAP is $37, the penalty would be 37 cents x 7 = $2.59 a month x 12 = $31.08 for the year. By, say, 2015, the penalty will still be based on the same seven uncovered months, but it will have increased overall because by then, as costs rise, that year's NAP is likely to be higher.
• If you don't sign up till the end of 2008, your penalty will be calculated on the 31 months (June 1, 2006 to Dec. 31, 2008) you were without coverage. So in 2009 you'd pay 1 percent of the 2009 monthly NAP x 31 x 12 and this amount will increase every year if the NAP rises.
• Because there will be only one enrollment period each year, from Nov. 15 to Dec. 31, each one that is missed will add a full 12 months without coverage to the penalty formula.

Will the national average monthly premium rise every year or could it come down?

It's possible that in some years the NAP will go down, if enough plans lower their premiums. But it's also true that under the law Medicare has the right to increase the penalty in future years to a percentage higher than the 1 percent of the NAP now in effect. As nobody yet knows what may happen, our chart is based on premiums rising by $5 a month per year, which may over- or underestimate the actual amounts of the penalties.

What if I'm not eligible for Medicare yet?

You'll be able to sign up for Part D at the same time as you sign up for Part B (doctor's visits and outpatient care) when you turn 65 or become eligible through disability. A late penalty will apply only if you miss that enrollment period.

I have drug coverage under a Medigap policy. Why should I sign up?

You have the right to continue drug coverage under your supplemental policy. But in most cases this coverage is not as good as Medicare's, so you might face a late penalty if you join Part D after the May 15 deadline. You should have received a letter explaining your options. If not, check with your insurer.

I live abroad. Will I face a penalty when I return to the U.S. and join a Medicare drug plan?

No. Medicare beneficiaries cannot enroll in Part D while living abroad. When you resume residence in the United States, you will not face a late penalty, provided you join a Medicare drug plan within 63 days of your return.

I just found out that my income is low enough to qualify for Extra Help. Can I still apply?

Yes, but do so as soon as possible, even though applications for Extra Help are accepted at any time. (This program offers a generous benefit to people with limited incomes and assets. The income limits for 2006 are about $1,225 a month for single people or $1,650 for married couples.) Call (800) 772-1213 or visit socialsecurity.gov.

If you apply now, you probably won't get a decision on whether you qualify by May 15. Medicare officials advise signing up with a plan before then to avoid a late penalty. If you qualify, you'll be refunded the difference between payments you've made and the much lower amounts you'd pay under Extra Help.

I'm still confused by Part D. How can I choose a plan?

All you need is your zip code and the names of all the drugs you take, plus their dosage and how often you take them. Giving this information at the Medicare hotline, (800) 633-4227, or entering it online into "Compare Medicare Prescription Drug Plans" at medicare.gov will help you find a plan. Or you can call your State Health Insurance Information Program (SHIP) for free personal help. (The Medicare hotline will give you the local number to call, or you can find it at shiptalk.org.)