What effects the health care law has had and what's to come

— -- Two years after President Obama signed the Patient Protection and Affordable Care Act, some provisions have taken effect, while others still have two years to wait.

In a recent poll by the non-partisan Kaiser Family Foundation, two in three Americans said they have not been affected by the law yet. Only 14% said they have benefited; 21% said they have been affected negatively.

Here's a look at some provisions with the broadest potential impact:

Already in effect

Pre-existing conditions. People uninsured for at least six months can join a new federal or state insurance plan. Children with pre-existing conditions must be covered.

Lifetime limits. Insurers cannot impose lifetime dollar limits on essential benefits, such as hospital services. More than 20,000 people hit their lifetime limits in 2009.

Preventive care. All new health plans must provide certain preventive services, such as mammograms and colonoscopies, without deductibles or co-payments. This affected about 54 million people in 2011.

Young adults. About 2.5 million young adults without private insurance can stay on their parents' plans until they turn 26.

Seniors. About 4 million seniors who reached the Medicare prescription drug coverage gap received a $250 rebate check in 2010. More than 3.5 million who hit the coverage gap in 2011 have received a 50% discount on brand-name drugs. More than 32 million seniors have received free preventive services, such as annual wellness visits.

Early retirees. Employers are eligible for federal assistance to provide health coverage to early retirees not yet eligible for Medicare.

Medicaid. States are eligible for federal aid to cover certain additional low-income individuals and families.

Small business tax credits. Up to 4 million small businesses are eligible for federal tax credits if they offer insurance coverage to their workers.

Health care costs. A study by Aon Hewitt estimates that the law raised costs by an average of 1.5% in 2011. Projection for 2012: 0.6%.

Effective in 2014 and beyond

Insurance exchanges. Federal and state health insurance exchanges will offer a marketplace of insurance options for people without employer-sponsored coverage.

Individual mandate. Most people will be required to buy insurance or pay a penalty.

Pre-existing conditions. Insurers will be prohibited from denying coverage to anyone because of a pre-existing condition.

Annual limits. Insurers issuing group plans and new individual-market plans will be banned from imposing annual limits on essential benefits.

Medicaid. The program will be open to Americans with incomes up to 133% of the federal poverty level — now about $15,000 for individuals and $30,700 for a family of four.

Tax credits. People with incomes up to 400% of poverty — now about $44,680 for individuals and $92,200 for a family of four — will be eligible for tax credits.

Newly insured. The Congressional Budget Office estimates that by 2016, the law will increase the number of Americans with health insurance by 30 million to 33 million.