MAJOR HEALTH CARE REFORMS KICK IN TODAY…. When the Affordable Care Act was signed into law last March, there were legitimate concerned that many of its key provisions wouldn’t take effect for years. That said, it’s wrong to assume major advances aren’t already happening.

Almost immediately after the legislation received President Obama’s signature, new consumer protections and benefits kicked in — young adults have been able to stay on their family health care plan through their 26th birthday; children with pre-existing conditions were no longer facing discrimination; and “rescission” practices were curtailed.

But as 2011 gets underway, even more worthwhile changes are taking effect, starting today.

The new year will bring important changes to U.S. health-insurance rules, as new provisions related to last year’s massive health-care overhaul take effect.

The new rules are designed to help those caught in Medicare’s “doughnut hole,” offer seniors more preventative care, and limit how much of their customers’ money health-insurance companies can keep for overhead and profit.

They all go into effect on Saturday.

These reforms may not appear especially sexy or high profile, but we’re talking about some pretty important provisions. Seniors who’ve been stuck in prescription-drug “doughnut hole,” will, for example, receive a 50% discount on the price of brand-name prescription drugs starting today. On a related note, seniors will also be eligible, starting today, for free “preventive services” screenings, including cancer tests like mammograms, and annual check-ups.

Of particular interest, on a systemic level, is the introduction of the new “medical loss ratio,” which sounds more complicated than it is. This new rule forces private insurers to spend 80% to 85% of the money we pay them in premiums on paying for* actual medical care to its customers, rather than everything else (profit, marketing, executive salaries, overhead, etc.). In recent years, some insurance companies were spending as little as 50% of their premium dollars on their customers.

Americans almost certainly won’t notice the shift resulting from the new medical loss ratio, but it’s expected to make a pretty big difference, and it’s one of the provisions that drew the loudest howls from the insurance companies and their congressional lackeys.

Taken together — the reforms that took effect in 2010, coupled with the measures that kick in today — we’re talking about some major positive changes to the system. All of these reforms, by the way, tend to be pretty popular — the larger concerns about the ACA notwithstanding — but are nevertheless being targeted by congressional Republicans, who want to eliminate the benefits entirely.

Good luck with that, GOP.

* Update: Thanks to martin for the recommended clarification.

Steve Benen

Follow Steve on Twitter @stevebenen. Steve Benen is a producer at MSNBC's The Rachel Maddow Show. He was the principal contributor to the Washington Monthly's Political Animal blog from August 2008 until January 2012.