BOSTON - At least half the state's uninsured residents may not have signed up for health insurance, less than a week before most people must have enrolled in a plan or face a penalty.

As of Nov. 1, about 200,000 people have enrolled in health insurance plans offered by the state or private insurers, according to the Commonwealth Health Insurance Connector Authority. It is estimated that between 400,000 and 600,000 people were uninsured as of Jan. 1.

Massachusetts residents must have health insurance by Dec. 31. People not insured by Nov. 15 face the loss of their $219 personal income tax exemption. The requirement is part of the landmark health care reform law passed in April 2006.

Richard Powers, communications director for the Connector Authority, said the state has worked hard to get people enrolled in time.

"We've made reasonably good progress in the first year (since the law was passed), but there's a lot of work to do," Powers said. "It's a marathon, not a sprint. It will take several years to implement."

To boost awareness of the deadline, the Connector Authority launched a $600,000 media campaign. It also recently mailed 3.3 million postcards to tax filers and has held 10 clinics across the state to help people sign up for health insurance plans.

The most recent enrollment opportunity was for North Shore residents and held at North Shore Community College in Lynn. Joan Fallon, the Connector Authority's chief communications officer, said more than 50 people showed up for the Thursday night clinic, which lasted four hours.

John McDonough, executive director of Health Care for All, acknowledged it's hard to reach everyone but said the state could have done more.

"The state and all of its partners have made a vigorous, aggressive, unprecedented, good-faith effort," McDonough said. "There's still a lot more to be done. There are still a lot of folks who haven't gotten the message."

The reach of the state's early ad campaign was too limited, he said.

"We think there ought to be a more aggressive radio and television campaign beyond the Red Sox (games)," McDonough said. "Not all (of the uninsured) are sports fans."

Reaching the state's uninsured people has not been an easy task, according to people enlisted to enroll them.

Joseph McManus, president of Lawrence General Hospital, said enrollment has been building steadily all year. He said enrollments in October, the month before the deadline, were double what they were in February. But there are still people who won't be reached in time.

"We're guardedly optimistic that the health services community and mailings have raised the awareness that people who are uninsured have the opportunity to sign up," McManus said.

Local community groups are also working with the Connector Authority to reach out to the uninsured residents.

Network Health, a nonprofit Medicaid managed care organization, has reached out to uninsured people across Essex County through local community groups such as the Lawrence Community Action Council.

Wendy Bueno-Gomez, a community outreach representative, said getting to people when it is convenient for them has been difficult.

"Their availability is a challenge," Bueno-Gomez said. "We've been doing this for a year. But trying to get to people who work two jobs - you need to have people working 24 hours."

In April, Bay State residents will have to indicate on their tax returns whether they have health insurance. If they don't, they will lose their $219 personal exemption. In subsequent years, they may have to pay a penalty equal to half the cost of the least expensive insurance available.

The Nov. 15 deadline exists to ensure people enroll early enough to have their insurance in effect to meet the Dec. 31 requirement.

Massachusetts residents have to buy insurance through a company, such as Blue Cross/Blue Shield, or through the Connector Authority.

Among the Connector Authority options: Commonwealth Care is private health insurance subsidized by the state for people earning less than 300 percent of the federal poverty line - about $61,900 for a family of four.

Commonwealth Choice features inexpensive insurance with pared-down coverage. Insurers offering this include Blue Cross, Harvard Pilgrim and Fallon Community, Neighborhood and Tufts health plans.

Approximately 200,000 people have signed up for health insurance through the state, Powers said. So far, 133,000 have enrolled in Commonwealth Care, 55,000 in MassHealth - the state Medicaid program - and 10,200 in Commonwealth Choice.

The Connector also estimates an additional 10,000 to 20,000 have purchased health insurance directly through private companies. The state expects to have enrollment figures in December.

It's unclear how many of those people were uninsured or are leaving plans offered by their employers that do not meet the state's minimum requirements.

How to enroll:

1. Fill out a Medical Benefits Request form. They are available at local hospitals and community health centers, or can be downloaded at www.macommonwealthcare.com. The Commonwealth Health Connector will send you a letter telling what you are eligible to receive.

2. Go to 1-877-MA-ENROLL or www.macommonwealthcare.com.

3. Choose your health plan and doctor.

Source: Commonwealth Health Insurance Connector Authority.