Paying taxes is never fun. Once you retire, though, this irksome obligation becomes especially painful. Rather than sharing a portion of your earnings, you'll be sending Uncle Sam a piece of the hard-earned savings you were banking on to carry you through your golden years.

It's surprising, then, that tax planning is often overlooked by retirees. "It amazes me how much time people spend picking investments, pouring over stock reports and mutual fund reports, but they don't think about taxes," says Dean Barber, owner and chief investment officer of Barber Financial Group in Lenexa, Kan. "I always tell them, it's not important how much money you make, it's important how much you get to keep."

Take, for example, Social Security income. It's a benefit funded by taxes that you pay throughout your working life, yet once you start receiving it, you could get taxed yet again. "Seniors hate that worse than anything," says Ed Slott, a Rockville Centre, N.Y.-based certified public accountant and author of "Your Complete Retirement Planning Roadmap." The pain could be substantial: Generally speaking, you owe Uncle Sam tax on up to 85% of your Social Security benefits once half of your benefits and the rest of your income — including dividends and interest on taxable investments and withdrawals from tax-deferred accounts, such as IRAs — exceed $34,000 for a single filer or $44,000 for a married couple, filing jointly. (Click here for more details.)

The good news is that some careful planning could help reduce the hit. Here are five smart (and perfectly