The New Year brought new health insurance coverage for millions of Americans, but rule changes and other developments continue to affect Obamacare.

Healthcare coverage for millions of Americans went into effect on Jan. 1 under the Affordable Care Act (ACA). Although enrollment for new plans began in October, last-minute developments continue to affect the ACA, also known as Obamacare. Here are four of the latest changes.

By the end of December, more than 2.1 million people had signed up for private health insurance plans through online state and federal exchanges. This falls more than 1 million people short of the government’s projected number for the first three months of enrollment.

The online health insurance exchanges were created to make it easier for individuals and small employers to shop for insurance coverage. But a string of problems with the websites may have slowed enrollment. At this point, it’s unclear whether the exchanges will reach their March 2014 goal of 7 million sign-ups.

In addition to the exchanges, in October and November 3.9 million people became newly eligible for Medicaid and the Children’s Health Insurance Program (CHIP). It’s unknown how many have actually enrolled in these government-funded programs for low-income people and their children.

Medicaid enrollment numbers would probably have been higher if it weren’t for a Supreme Court decision to allow states to opt out of expanding the program under Obamacare. Currently, 26 states have said no to the expansion of Medicaid or have yet to decide. This includes Florida and Texas, two of the states with the largest number of uninsured citizens.

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The Obama administration also announced that it would delay the individual mandate for people whose insurance policies have just been canceled. Instead of being required to buy health insurance through the exchanges or face a penalty, these people may qualify for a one-year “hardship exemption.”

Health and Human Services Secretary Kathleen Sebelius said in a letter that the people affected amounted to “a small number” and that “the population of individuals with canceled plans who do not have quality, affordable coverage for 2014 is clearly shrinking.”

This policy change would also allow people whose individual policies were canceled to purchase a catastrophic plan, which usually has a lower premium but provides coverage mainly for high medical costs associated with emergency care.

Previously, these plans were only available to people under 30 or those with a “hardship exemption,” which is granted for situations including homeless, an eviction within the past six months, and the recent death of a close family member.

The recent rule change added one more condition to that list: “Your individual insurance plan was canceled, and you believe other Marketplace plans are unaffordable.”

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Shortly before the start of healthcare coverage in the new year, the Supreme Court exempted certain religious groups from the ACA’s mandate that they provide birth control for their employees or students.

The Affordable Care Act requires employers to provide insurance that includes free preventive care, including birth control. Companies that don’t comply with this mandate can face fines of $100 a day for each employee affected.

An order by Supreme Court Justice Sonia Sotomayor temporarily prevented the government from requiring that the Denver-based Little Sisters of the Poor provide coverage for contraceptives as part of its employee health insurance plan.

In response, the administration said the Justice Department had already determined that churches like this are exempt because their health insurance plans are self-funded.

Sotomayor’s decision was bolstered by a U.S. Court of Appeals for the District of Columbia Circuit stay on the birth control mandate, affecting Catholic-affiliated groups like the Archdiocese of Washington, D.C.

The Supreme Court is also expected to hear two cases involving businesses who have raised religious objections to the birth control requirement.

One stems from Hobby Lobby, Inc., an Oklahoma City-based chain of arts and crafts stores with 15,000 full-time employees. The other is the Pennsylvania-based Conestoga Wood Specialties Corp., which employs 950 people.

In the lower courts, Hobby Lobby won its case while Conestoga Wood Specialties lost. The Supreme Court will hear the combined cases in late March, with a decision expected by summer.

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Though millions of Americans already have new coverage, there is still time to sign up for health insurance through the state or federal exchanges. The open enrollment period ends March 31, 2014.

For those who signed up last year, many insurers have extended the deadline for paying the first month’s premium to January 10, 2014.

However, not all insurers have extended the payment deadline, and some may still require people to have paid by Dec. 31 in order to start receiving coverage on Jan 1. Enrollees should check with their insurance companies directly.