In the course of planning for retirement, you may come across misinformation that leads you to make poor decisions. There are a lot of dangerous myths circulating about retirement, but these four in particular could really set you up for disaster during your seniors years.

1. You can get by on Social Security alone

Many seniors assume they'll be able to cover their living costs based on the benefits they collect from Social Security. In reality, those benefits are likely to fall short.

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Even if you're willing to live frugally, Social Security will only replace about 40% of your pre-retirement paycheck if you're an average wage-earner. Most seniors, however, need a lot more money than that to stay afloat and cover their expenses.

If you're still not convinced, map out a sample retirement budget and see if 40% of your current paycheck will cut it. If not, you'll need to ramp up on the retirement savings front to help ensure that you have enough money to pay for your various needs.

2. You'll get to keep your Social Security benefits in full

You may be aware that if you save for retirement in a traditional IRA or 401(k) plan, your withdrawals will be subject to taxes. But many seniors are shocked to learn that Social Security benefits are taxable as well.

This isn't to say that all seniors pay taxes on those benefits. If they're your only income source, you're probably safe in that regard. But if you're a moderate earner, you could face taxes on up to 85% of your benefits, and that's just at the federal level. There are also 13 states that impose taxes on Social Security income.

3. Healthcare will get less expensive once you're on Medicare

Many people assume that Medicare is extremely affordable or even free. Not so. In addition to the cost of premiums, deductibles, and copays, you'll also need to cover the cost of services Medicare won't pay for, like dental care.

In fact, all told, the average 65-year-old opposite-gender couple retiring today will spend $300,000 on healthcare in retirement, reports Fidelity. Even if you break that down over 20 years, that may be a lot more than what you're spending today, especially if you happen to have good insurance.

4. You'll spend so much less once you stop going to an office

There are definite costs involved in going to an office -- paying for transportation, maintaining a business wardrobe, and buying lunch when everyone else is doing it. But don't assume you'll spend less once you stop working.

While not having an office to report to could lower your expenses to some degree, you'll also have more free hours to fill once you retire. And so you may end up spending a lot more money just to stay occupied. Plus, there's a good chance your utility bills will rise once you stop going into an office and start spending more time at home.

If your goal is to retire with confidence, you can't afford to fall victim to misinformation. Getting to the bottom of these myths could spare you a world of financial stress once your career comes to a close.