A 65-year-old couple retiring this year is estimated to need about $240,000 to cover medical expenses throughout retirement, according to a study of retiree health care costs by Fidelity Investments. Much of that comes in the final years of retirement.MYTH NO. 3: You'll need far less income in retirement to maintain the same standard of living. This may be true in some cases, but it could be a life-changing mistake to count on it. Surveys of retirees have found that many spend as much or more in the early years of retirement than before they retired. Because retirement spending habits vary so widely, many financial advisers frown on the traditional rule of thumb that you need 70 to 80 percent of your pre-retirement income to maintain your lifestyle. If you reach retirement and find that was a bad guesstimate, "you may quickly find yourself looking for work," says Tim Steffen, director of financial planning for Baird Private Wealth Management in Milwaukee. You may not need 100 percent of your earlier income. But take some time to analyze what you expect to spend in retirement in order to lessen any anxiety. MYTH NO. 4: You can claim Social Security early and still get full benefits later. Applying for benefits as soon as eligibility begins at age 62 will entitle you to monthly checks immediately. But when you claim early, your benefits will be 25 percent less than if you had waited until your full retirement age and 75 percent to 80 percent less than if you'd been able hold off until 70. That remains the biggest misunderstanding among people using the AARP's Social Security Q&A tool, http://www.aarp.org/ssqa . "This myth is not only so wrong but also dangerous," says Jean Setzfand, AARP vice president for financial security. "When consumers claim their Social Security benefits, they lock in those benefits for life."