A short-term disability that turns into a long-term one can seriously sideline your finances. And just in case you think it can't happen to you, consider that the U.S. Census Bureau reported in 2000 that nearly 20% of the population had some type of long-lasting condition or disability. (And, no, "road rage" doesn't count.)

Many employers provide short-term disability coverage; some provide long-term disability as well. However, these plans only cover a percentage of your salary while you're out (usually around 60%) and are restricted by weekly or monthly limits. Plus, when employers pay the premium, the income you receive is taxable.

If a short-term disability turns into a long-term one, and you don't have additional coverage, you'll be forced to drain your savings (yes, including your 401(k)) before Social Security will lend you a financial hand.

To augment your coverage with supplemental long-term disability insurance, start shopping at your office.

If your employer offers the chance to purchase additional coverage, it'll likely be the cheapest you'll find. (Mark your calendar, because you can sign up only during your plan's open enrollment window.) If you can't buy more peace-of-mind via the office, see the Federal Citizen Information Center's info sheet disability insurance shopping tips and links to help you check out insurers. And here's a long-term disability insurance checklist to help you assess policies you're considering and record key points that will help you compare coverage.

Yes, we know that sounds about as exciting as watching water freeze. But (unfair scare tactic alert) consider that watching water freeze may be about the only entertainment you'll be able to afford if you do fall ill and are unable to work for an extended period.

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Foolish personal finance expert Dayana Yochim is the author of The Motley Fool's Guide to Couples & Cash. The Fool has a disclosure policy.