The top of the year-end checklist typically includes making certain to send a donation to a favorite charity by Dec. 31.

This year, though, some accountants say you don't want to make those donations until January - if you're betting on higher tax rates in 2013.

But what about grabbing some money from an IRA? Will you or an older family member withdraw the entire required minimum distribution from your IRA by Dec. 31? This is one where you don't want to drag your feet.

Every year, many investors simply miss the deadline for taking the required withdrawals from their IRAs, said Ken Hevert, vice president of personal retirement products for Fidelity.

"It can really get complicated," Hevert said.

The issue isn't just that you're missing out on getting extra money to cover bills. You could be creating a very costly tax headache, too.

Retirees age 70 1/2 and older must follow required distribution rules when it comes to IRAs. The same can apply to a 401(k) if you're retired and no longer working at that company.

Typically, investors who must take required minimum distributions have until Dec. 31 each year to withdraw the full amount.

But if you turned 70 1/2 in 2012, you'd have until April 1, 2013, to take that required first distribution, and you'd have to take one for 2013 as well.

The distribution is calculated based on life expectancy and how much retirement savings you've built up.

IRA experts say the IRS is aware of "growing non-compliance" with IRA distribution requirements, too, and is expected to crack down further to capture losses in tax revenue.

More than 250,000 taxpayers fell short of taking the required distributions in 2006 and 2007, by almost $350 million, according to federal statistics.

The estimated tax revenue loss those two years was about $174 million, according to a 2010 report by the Treasury Inspector General for Tax Administration.

This issue becomes more important as Baby Boomers age. The required minimum distribution can boost your taxable income in a given year.

The required minimum distribution rules do not apply to Roth IRAs. There's no age at which you must start taking distributions.

Various online calculators and financial planners can work with you to figure out distributions.

For example, if you're 71 now and had $100,000 in an IRA as of December 2011, the required minimum distribution could be $3,773.58 in 2012, depending on your situation.

Hevert said about half of Fidelity's IRA customers set up a system with the firm so that Fidelity automatically sends the required minimum distribution. But about half make sure to take those distributions on their own.

Yet, time can go by and you forget to do what's necessary.

As of Dec. 9, just under half of Fidelity's more than half a million IRA customers who are required to take distributions for 2012 had not yet taken the full amount.

Granted, many may plan to do so in the next week or so - but others can forget.

The rules can be extremely confusing, too.

Pay special attention if you took a lump sum from your pension plan. Retirees from General Motors, Ford Motor and others who traded in monthly pension checks for lump-sum distributions - then rolled that money into IRAs - will need to watch the distribution rules as well.

Older retirees who took lump sums from pension plans will be thankful to know, though, that the required minimum distributions for 2012 won't be based on any new money that was rolled into the IRA this year.

The required distribution is based on the previous year's balance. So for the 2012 tax year, that's the balance as of Dec. 31, 2011.

"Your 2013 distribution will be based on the Dec. 31, 2012, balance," said Ed Slott, an IRA expert whose website is www.irahelp.com.

There are other factors to consider if you've inherited an IRA from Mom or Dad or a beloved aunt or uncle.

If you inherit an IRA from someone other than your spouse, the rules are complicated, and you may not get to wait until 70 1/2 to take out money. Say Dad died at 79 in 2011 and his daughter Mary is 50 and is the beneficiary. Mary has until the end of 2012 in this example to take the required minimum distribution.

If you forget to take a required minimum distribution, the tax penalty is steep.

The penalty is 50% of the difference of what you should have taken out and what you took out.

But it is possible to correct the problem by filing Form 5329, Additional Taxes on Qualified Plans (Including IRAs) and other Tax-Favored Accounts. You'd request a waiver of the 50% penalty.

If you should have withdrawn $1,000 from that IRA but didn't take out any money, the penalty would be $500.

The form has six pages of instructions. But the IRS can waive part or all of that penalty if you show you made a reasonable mistake and took remedies to make certain to take the required minimum distributions.

It's best to avoid the mistake.

Where to find help online.

IRS Publication 590 for rules about IRAs. www.irs.gov

Some useful retirement web sites: www.401khelpcenter.com and www.irahelp.com.

If you forget about a distribution, talk to your financial planner or accountant and see Form 5329, Additional Taxes on Qualified Plans (Including IRAs) and other Tax-Favored Accounts. You'd request a waiver of the 50% penalty.

Bankrate.com has a calculator to help you figure required distributions.

USA Today