WASHINGTON — There's no question that our tax code causes a lot of confusion. But don't let confusion or misinformation lead to an audit or cause you to miss out on a deduction.

For example, here's a comment I received from someone in one of my recent online discussions: "I believe the person hoping to pay off their house early and get a mortgage interest deduction for a vacation or second home is mistaken, as that deduction is only for your primary residence."

Nope. Even if you have paid off the loan on your primary residence, the mortgage interest on a second home is generally deductible, according to the IRS. In fact, you don't even have to use the second home.

However, in general, if you rent out a second home for part of the year, you also must use it as a home for a short time during the year for it to qualify — for more than 14 days or more than 10 percent of the number of days that year that the home is rented at a fair price, whichever is longer. Otherwise, it is considered rental property, and you cannot deduct the mortgage interest.

Get IRS Publication 936, "Home Mortgage Interest Deduction," for more information (read it online at www.irs.gov).

During that chat I received other tax-related questions, such as: "I'm confused about spousal IRAs and the age-50-plus catch-up provision."

Well, a working spouse is allowed to make a contribution to a separate IRA for a spouse with little or no income if they file a joint return. The total contribution to both your IRA and the spousal IRA is limited by factors such as your taxable compensation, contributions to a traditional or Roth IRA and your age. For tax year 2006, you can contribute up to $4,000 to a spousal IRA. If your spouse is at least 50 you can contribute up to $5,000. This limit also applies to the working spouse.

"My family moved to Maryland in 2006. We already had 529 plans for our kids, but now we find out that Maryland allows you to deduct contributions to a Maryland 529 plan. Should we a) switch everything over to a Maryland plan to get the tax benefit, b) keep on growing the other plan, or c) just open a separate Maryland 529 plan?"

Never make an investment decision based solely on taxes. But in this case, yes, factor in the state tax deduction. For Maryland, that is limited to $2,500 per account each year.

Consider a number of factors before moving funds, says Joseph Hurley, founder of www.savingforcollege.com, a Web site where you will find information on 529 plans.

For instance, compare returns for the two state plans, keeping in mind that past performance is no guarantee of future returns. Compare investment options. Also take into account fees and expenses. "Over some period of time, the investment performance is going to be a bigger factor than a state tax deduction," Hurley says.

To compare state 529 plans, go to www.savingforcollege.com, click on the link for "529 Plans" and then click on "Compare 529 Plans."

Finally, should you be fearful of filing electronically? One reader is.

"I'm very leery of e-filing my tax return because I just don't want to give the government my IP (Internet Protocol) address, what with all the illegal surveillance that has been authorized by the current administration."

When you file your tax return electronically, it doesn't go directly to the IRS. It goes to an Intermediate Service Provider for processing, then to a transmitter that sends only your return information to the IRS, according to IRS spokesman James Dupree.

"The security of taxpayer accounts and personal information is a top priority for the IRS," he said. "It is the responsibility of each authorized IRS e-file provider to have security systems in place to prevent unauthorized access to taxpayer accounts and personal information by third parties. Your IP address is not recorded or sent forward."

There you go.