Image: Mature couple calculating expenses © Abel Mitja Varela, the Agency Collection, Getty Images

Wouldn't you love to retire right now? Unfortunately, retiring successfully means planning carefully and accurately for the expenses you'll incur in your post-working years. Along the way, a number of bumps could throw your plan off track.

1. Stock market drop

After the crash of 2008, it's clear that we can't simply hope that the stock market will always rise or stay level, and that's especially true the closer you are to retirement. One of the first changes you may have noticed after the crash was the hit to your investment portfolio. The Dow Jones Industrial Average plummeted from its intraday height of 14,280 in October 2007 to 6,443 in March 2009, a staggering 7,837-point difference.

Not only did investments take a big hit; for many people, the ability to earn an income, and thus invest further, also suffered. According to the Bureau of Labor Statistics, the 2007-2009 recession saw the steepest increase in the unemployment rate compared with other post-World War II recessions. Suddenly, many Americans found themselves with portfolios worth a fraction of what they had been a few months earlier -- and also without a way to increase their savings to make up for the deficit.

2. Boomerang kids

According to studies by the Pew Research Center, the number of Americans living in multigenerational homes has been increasing since 1980. In fact, this last recession marked the largest increase in the number of multigenerational households in recent history, with the number rising to 51.4 million in 2009 from 46.5 million in 2007. With the tough job market, increasing student debt loads and the overall trend of later-in-life marriages, more young adults are moving back in with their parents.

This means parents are bearing the burden of additional living expenses. The average cost of raising a child born in 2010 until age 18 in the United States averages $226,920, according to U.S. Department of Agriculture estimates (.pdf file), and the additional expenses of housing a child beyond that age can really eat away at parents' finances.

3. Divorce

The Centers for Disease Control and Prevention reports that as of 2009, the divorce rate in the United States was about 50%. Not only is a divorce a huge lifestyle change, but the financial impact can be devastating. At minimum, a divorce means a shift in how a couple's income is allocated. For example, each partner may be paying for housing costs individually instead of together.

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A divorce sometimes means one partner may need to go back to work after years of working in the home. Retirement assets will likely be divided, and this is all before considering what the actual divorce will cost. A lawyer will likely charge hundreds of dollars an hour, and the less you and your spouse agree on the terms, the longer and more expensive the divorce process can be.

4. Lifestyle changes

If you've recently taken up an expensive hobby, such as traveling, you're obviously going to need more money than you may have estimated for your retirement. In addition, if your health deteriorates or you are diagnosed with a serious medical condition, you'll probably have to factor in the costs of health care and medications as well as additional expenses, such as accessibility adjustments to your home should you become disabled. Make sure that you keep up to date on what your medical insurance will cover and that you include the cost of premiums in your post-retirement budget.

5. Poor planning

This is the most commonly cited reason for delaying retirement. You need to be aware of the potential problems that may throw off your retirement plans (like the ones listed above), and it's crucial that you hedge your investments and plan as best as you can for these surprises. Luckily, making and sticking to these plans isn't as complicated as it might seem. Start educating yourself by reading informative materials, then seek out retirement consultants to make sure you're on track.

The bottom line

Don't be intimidated by your finances. The earlier you get started, the easier saving for your retirement will be and the less disruptive it will be to your present life. Inform yourself and create a reasonable plan so you'll be ready to retire before you know it.

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