Energy credit If you haven't taken advantage of a tax credit for making "green" improvements to your home, such as insulation or energy-efficient windows, you have until the end of the year to do so. The expiring credit is worth up to $500.

Retirement If you haven't maxed out on your 401(k) contributions, it's not too late to boost your contributions in the last few weeks of the year, Rempe says.

Not only is this good for your future retirement, but contributions reduce the amount of income subject to tax. (Your 401(k) money, though, will be taxed when you withdraw it in retirement.)

Depending on your income or whether you have a retirement plan at work, you may be able to deduct contributions to a traditional IRA. You have until the tax deadline — April 17 next year — to make an IRA contribution for 2011. (The deadline is extended by two days because the usual deadline falls on a weekend followed by a holiday.)

Roth conversions Many people took advantage last year of a change in the law that allowed high-income workers to convert a traditional IRA to a Roth IRA, which permits tax-free withdrawals in retirement. A conversion, though, triggers a tax bill on the amount being converted.

For conversions done last year only, taxpayers had the option of splitting the tax bill over their 2011 and 2012 returns.

"This will be the first year they have to pay the tax on that," says Bob Meighan, vice president of TurboTax. "Make sure you are aware of it and have the money available when it becomes due."

Look ahead At the end of next year, many Bush-era tax cuts are set to expire. Congress is expected to wait until after the election to act.

Next year will be the "tsunami of tax-law changes," Jackson Hewitt's Steber says, adding that it likely will mean higher taxes in 2013.

One new tax on the horizon: a 3.8 percent Medicare tax on investment income that's part of the health care reform act, says CCH's Luscombe. The tax will apply to singles earning more than $200,000 and couples with incomes over $250,000. Capital gains tax rates also expire that year and could rise from 15 percent to 20 percent for these households, too, he says.

With that in mind, Luscombe says, you might consider moving money into tax-free municipal bonds or a Roth IRA to avoid taxes on gains.

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