Smart investors take advantage of every edge they can find. Right now, you have a lot of things going for you when it comes to saving and investing for your future. But there's no guarantee that these opportunities will last forever -- so it's critical to plan for whatever contingencies may happen.

One harsh example of a worst-case scenario is in loan forgiveness programs for teachers, nurses, and other labor-starved occupations. For years, states have offered incentives to students who entered these fields after they graduated by forgiving some of the loan debt they incurred during school. Now, though, many states can't afford to continue these programs. That's leaving folks who were counting on those incentives in the lurch, stuck trying to pay back their debt on their own.

While that example won't have a direct impact on many people, other possibilities would affect nearly everyone. Here are three things that investors have counted on for years, and how you can prepare yourself for their potential disappearance:

1. Special tax rates on dividends
Since 2003, investors have enjoyed special low rates on dividends. Currently, the maximum rate on dividends is 15% -- the same rate that applies to long-term capital gains. Before then, taxpayers paid the same tax on dividends that they paid on interest and other forms of income, at rates up to 35%.

Clearly, that move provided a huge incentive for investors to own dividend-paying stocks -- especially stocks with fairly high yields. Consider the annual tax savings on these dividend stocks:

Stock

Value of 1,000 Shares

Annual Dividends
on 1,000 Shares

Taxes Saved Annually
Due to 15% Dividend Rate

Altria (NYSE:MO)

$16,850

$1,280

$256

Duke Energy (NYSE:DUK)

$14,440

$920

$184

Southern Company (NYSE:SO)

$29,910

$1,698

$340

Vodafone (NYSE:VOD)

$18,940

$1,173

$235

Source: Yahoo! Finance as of June 11. Dividends based on trailing dividends paid in past 12 months. Savings assumes taxpayer in 35% tax bracket.

The current administration proposed increasing these taxes to 20% for those making more than $250,000. There's always the potential, however, that the entire distinction between dividends and ordinary income will go away, costing taxpayers the same amount they've saved under the lower rate. If that happens, you'll want to make sure you have your dividend stocks in tax-favored accounts to protect you from higher taxes.

2. No more Roths?
As one example of such a tax-favored account, the Roth IRA is one of the best deals available for tax savings. If you follow all the rules, you'll never have to pay taxes on any income from your Roth investments, a benefit that could last your entire lifetime. Those who put high-growth stocks like Apple (NASDAQ:AAPL), Hansen Natural (NASDAQ:HANS), and PotashCorp (NYSE:POT) into Roth IRAs 10 years ago have seen their money grow tenfold and more -- all tax-free.

To my knowledge, the government hasn't seriously talked about discontinuing Roth IRAs. But every tax dollar you save by using a Roth costs the government a dollar of revenue -- and lost taxes will increase as Roths become bigger and more widely used. With record budget deficits, it's only a matter of time before the government starts scaling back on expensive perks like this. Before that happens, you'll want to take maximum advantage of Roths while they last.

3. Easy 10% returns on stocks
We're all familiar with the studies showing the long-term average return on stocks is close to 10%. But don't rely on earning that rate over your lifetime, or it could cost you. Over the 40 years ending Dec. 31, 2008, for instance, the S&P 500 returned an average of about 9%. While that single percentage point may not seem all that important, over 40 years, it would have left you with much less money.

To prepare yourself for the possibility of lower returns, consider two options. You can save more, allowing for a worst-case scenario that may prove better than you expected. Alternatively, looking harder for better-performing stocks may help you eke out extra returns, even if the overall market averages don't meet their historical trends.

As investors, you always need to prepare for change. As long as you know what to expect, you can successfully adjust to whatever the future may bring.

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