When it comes to researching Medicare options, many personal financial educators refer people to the Medicare.gov website. The official US government website for Medicare is by far the most comprehensive of all information portals.

But it can be overwhelming. Especially for the 11,000 men and women who turn 65 every day and become eligible for Medicare for the first time. For most, terminology is the equivalent of learning a new language. Medicare health plan options are more complex and varied than most are used to.

And there are some important things that the government website doesn’t tell you. For example, it does not clearly state the importance of your first enrollment in the plan. Nowhere on the website does it say that the Medicare plan choice can be irrevocable.

It also doesn’t really explain what questions to ask before choosing a plan. Medicare.gov does a great job of offering unbiased comparisons, like premium rates. But when it comes to subjective elements, these are something that the website obviously cannot address.

Anyone who has been eligible for Medicare for a few years will tell you that selecting the right Medicare plan isn’t easy. In fact, some industry estimates find that 25 to 40 percent of people change after making a decision. Navigating the complexity is especially difficult when you’re first eligible for Medicare. Even more so if your current or previous health care coverage consisted of some options preselected by your employer or union.

One of the features of Medicare.gov is the appearance of being able to connect directly with an insurance company. And while it stands to reason that ‘buy direct’ will be better and save you money, it’s simply not true. Quite the contrary. It could be a significant and costly mistake.

The following are things to keep in mind when using the Medicare.gov website shared by the American Association of Medicare Supplement Insurance, a national advocacy and educational organization.

1. Medicare.gov is much easier for Medicare Advantage (MA) plans to use. But that’s just one of the options available to you. It may or may not be your best option. For those who prefer to see any doctor or specialist, only a Medigap plan offers that option. For those who travel or spend time in another state, Medicare Advantage may not cover them outside of their home area.

2. The Medicare.gov website doesn’t make it easy to understand things that matter, like in-network, out-of-pocket costs, drug plan coverage, coordination with veterans coverage, and Medicaid. “In-network” is important if you decide a Medicare Advantage plan is best for you. Knowing which local doctors, hospitals, and especially specialists participate can be difficult to find on your own.

3. Medicare.gov plan comparisons seem very detailed. But they miss out on some important information that is vital. For example, the decision you make when you turn 65 could be irrevocable. Changing Medicare plans isn’t always possible. Medicare.gov doesn’t tell you what’s possible if you don’t like your choice or when you change your chosen plan. These are all very important things to know before deciding on an option.

4. Searching for prescription drugs on the Medicare.gov Plan Finder can be confusing for those who take multiple medications. It is especially important for the millions of people who take insulin medications.

5. Medicare.gov lists Medicare Advantage plan supplemental benefits (vision, dental, etc.). Unfortunately, there are few specific details of what is covered in terms of benefits and service providers.

Buying directly from an insurance company like UnitedHealthcare (NYSE: UNH), Aetna (NYSE: AET), Cigna (NYSE: CI) or Humana (NYSE: HUM), several of the leading ones, or calling an 800 number can or can that is not your best option. Is the person on the other end of the line a captive agent for the particular insurance company? Do they receive any incentive for all one particular plan over another?

Comparing Medicare plan options is always the smartest decision. A local Medicare professional who knows about local options, including Medicare Advantage options, Medicare Supplement, and prescription drug plans, can be an hour well spent. Today, most insurance agents host an online meeting to discuss options and answer questions.

The American Association of Medicare Supplement Insurance offers a national online directory that lists Medicare insurance agents. Access is free and private, unlike most websites that require you to enter information before displaying results. Whether you’re turning 65 or just have Medicare insurance questions you want answered, it’s a resource worth knowing.

That experience and local knowledge comes at no cost. And, the same plans that are available online or available directly from the insurance company can be sold by a designated agent with the particular company. Perhaps most importantly, it is available for the same cost.