We've all done it: built something beautiful with hard work and dedication, only to ruin it with one stupid mistake. For some people, we're talking about the loss of a woodworking project or a home-cooked meal. For others, the subject is retirement.

Read on to find out the most common retirement-damaging mistakes, and how to avoid them.

The Six Costliest Retirement Mistakes

  1. Not saving extra for healthcare. Too many people assume that, once they hit age 65, Medicare will pay all their health expenses. Not so. You still have to pay for Medicare premiums, as well as supplemental items such as Medigap, prescription drug coverage, and items not covered by insurance. Dental premiums are extra, and items like hearing aids are typically not covered. A 65-year old couple retiring in 2016 needed $260,000 for healthcare expenses, according to a Fidelity report. That's up from $245,000 in 2015. “How you plan for the aging process and the very real increasing costs has to be considered in any [retirement] plan,” says Peter J. Creedon, CFP®, CEO of Crystal Brook Advisors in New York City.
  2. Being lured by low income taxes. States like Florida, which have no income tax, attract retirees for a reason. But beware: those states find other ways to make up the tax gap. They likely have high sales and property taxes, all of which can eviscerate your retirement savings. Before you pack up, do the math and figure out what your best options are. There are cost-of-living calculators that will help you examine the price of gas and groceries, which you'll still have to buy in retirement.

  1. Retiring too early. Too many people retire once they hit a certain age. Unfortunately, you can’t stop working just because you hit age 65. “Deciding when to retire should not be taken lightly. A well-thought-through plan should be in place in terms of estimated spending needs in retirement, as well as a high degree of confidence that your funds will support those needs,” says Mark Hebner, founder and president of Index Fund Advisors, Inc., of Irvine, California, and author of Index Funds: The 12-Step Recovery Program for Active Investors. Before you leave the work world, sit down with a professional financial expert and examine how robust your retirement funds are. The expert will be able to tell if you can quit working, or whether, if you stop working now, you’ll be pushing carts at your local Wal-Mart (WMT) when you’re 80 years old. Don’t leave your job before doing this; the likelihood of getting hired in the same field becomes harder as you age.

  2. Spending too much too quickly. “While I can’t think of too many clients who reduce their spending in retirement, I know a lot who have increased it. Why? Their expenses, especially related to recreation and vacations, go up dramatically,” says Mack R. Courter, CFP®, founder and principal of Courter Financial of Bellefonte, Pa. If you’ve been living on a shoestring budget to afford your retirement, it might be tempting to let loose. Unfortunately, many retirees forget that they’re on a fixed income. A safe withdrawal rate is between 3% and 4%. Make sure you stick to that amount. Just because you’re retired doesn’t mean you don’t have to live on a budget.

  1. Supporting your adult children. When the economy tanked in 2008, many young people moved back home to save money. Unfortunately, a number of them are still there. Even if you’re not helping with your child’s car or student loan payment, you might still be spending a lot of money to provide support. Some estimates say that paying for groceries, utilities, and cell phone expenses can cost thousands each year. That’s money you could be saving or spending on your own needs. Some retirees are still providing support long after their children have kids of their own (see How Much Being a Grandparent Will Cost You). If you want to help your children, make sure it’s not at the expense of your own retirement. "Tell the kids that once they are out of college, they are on their own financially," says Brock Williamson, CFP, of Promontory Financial Planning in Farmington, Utah. "Supporting them past those years enables them to be unproductive members of society, and can become a large anchor holding back your own retirement objectives."

  1. Being too optimistic with your finances. Once you’ve retired, it’s easy to sit back and enjoy your golden years. Unfortunately, that optimism may end up hurting you. If you had high health bills this year, don’t automatically assume that next year will be better. If there are signs of your home losing its value, don’t put off looking at other options. It may be difficult to look at the cold, hard truth, but it could save you from spending money you’ll need later. “Having an accurate picture of your current spending before retirement will help you to avoid a nasty surprise if retirement brings a reduction in income, or possible additional expenses you never had before,” says Melissa Sotudeh, CFP®, wealth advisor at Halpern Financial of Rockville, Md.

The Bottom Line

If you’re putting in the work to build your retirement chest, you should put in the work to protect it. “New retirees generally find they still need to be good stewards of their resources,” says Russ Blahetka, CFP®, managing director of Vestnomics Wealth Management in Campbell, California. Before you make a costly mistake, consult a financial advisor who can give you unbiased advice. He or she may save you from losing your nest egg.