Maine Republicans are assailing President Barack Obama’s health care law by saying it amounts to a tax increase. Not only are they wrong, but it appears their memories are a little selective. Their own health insurance overhaul last year, which they will continue to champion on their campaign trails, included a tax.

If Republicans are going to argue against the Patient Protection and Affordable Care Act, they should first make sure they’re not also delegitimizing their own law.

The Republican argument stems from the fact that five justices agreed on Thursday that the penalty people must pay if they refuse to purchase health insurance is a kind of tax. Because Congress has taxing power, the requirement that virtually all Americans buy insurance is constitutional.

But even though the swing vote came from a conservative — Justice John Roberts Jr. — and even though Maine Republicans last year passed a health insurance reform bill, LD 1333, that included a provision to add a $4 charge to the monthly premium of Mainers with private coverage, some in the GOP argue the health care act is wrong because its legality is based on tax law.

“This massive tax hike will only destroy the American economy as it forces us over the financial cliff,” reads a press release from Gov. Paul LePage’s office issued after the U.S. Supreme Court ruled Thursday that Obama’s health care law is constitutional.

Maine Senate President Kevin Raye, who is running for the U.S. House, called it “an unprecedented coercive new tax.” Olympia Snowe, Maine’s retiring Republican senator, said it will “impose an onerous tax.”

The law, however, is not projected to equate to a tax increase for the vast majority of Mainers or Americans. Most people already have insurance through their employers, Medicaid or Medicare. An Urban Institute study found that of the 26.3 million people currently uninsured, about 70 percent of them qualify for tax credits to help them pay for a qualified plan.

Just 7.3 million people, or 2 percent of the population, will not be offered financial assistance under the health care law and will be subject to penalties if they do not obtain coverage. The idea that the health care law amounts to a tax hike for many Americans is simply wrong.

In fact, studies show that the law will lower costs for Americans. The nonprofit Families USA estimates that by 2019 more than 500,000 Maine families will be better off by an average $1,685 per year because of the law.

The misinformation-spreading by Republicans comes on the heels of them actually implementing a health insurance tax. Just a year ago, their health reform law aimed to lower costs for young, healthy Mainers by putting higher-cost policyholders in a special pool and then defraying the costs of their insurance by having a monthly tax of $4 assessed on all other policyholders.

The $4 tax was designed to replace a charge on health insurance claims that Mainers paid to keep the Dirigo Health program in operation. People legitimized it by saying it would be less than the annual Dirigo assessment. But it is still a tax.

No one likes the word “tax,” but Mainers should remember that our state’s transportation infrastructure, schools, police forces and much of our health care system all are possible because of tax dollars. Republicans should gather their facts before they claim the health care law means a tax increase. And if a health insurance tax is bad now, they should explain why it wasn’t bad in 2011.