Taxes are due April 18th, so many people are last minute filers....including me. Did you miss something that might save you money? There are so many tax laws that allow people to deduct more from their income that aren't published anywhere. Here are 30 last minute tips that might get you a bigger refund check.

First, some good news: This year's deadlines are unusually late. Because April 15 coincided with a District of Columbia holiday, 2010 tax payments are due Monday, April 18. The deadline for those with six-month filing extensions is Oct. 17.

Now for some bad news: Audits on wealthier taxpayers are likely to rise, say tax experts, while refund amounts are merely holding steady. As of mid-March, just over half of all 140 million-plus individual returns had been filed, slightly behind the total for last year, and the average refund continued to be about $3,000.

If you are racing to meet the April 18 deadline, here are some last-minute tips gathered from a broad array of tax preparers. We have identified eight deductions that many people overlook, eight audit triggers, six common mistakes, five reminders for investors and three ways to cut your tax bill right now. Plus, we offer a heads-up on the perils of offshore accounts.

8 Overlooked Deductions

1. State-tax refunds for AMT taxpayers. Taxpayers often forget that state tax refunds aren't taxable to those who owe alternative minimum tax, or AMT, for the same tax year, as long as the amount of the refund is less than the amount of state income tax disallowed under AMT.

2. Charitable donations, Part I. Donors may not deduct labor or time, but they may deduct expenses such as mileage or uniforms. Board members or chosen representatives also may deduct unreimbursed expenses for attending a conference or meeting. For details, see IRS publication 526.

3. Charitable donations, Part II. Employees who give to charities via payroll deductions at work frequently forget to include them on their personal return. "The number is not on the W-2 and there's no letter," says Melissa Labant, an expert with the American Institute of CPAs.

4. Health-insurance premiums for the self-employed. For 2010 only, people who are self-employed and have deductible health-insurance premiums may also deduct them against Social Security taxes on Schedule SE. For 2010 and after, these same taxpayers may deduct premiums for a child under age 27 at the end of the year, even if the child isn't a dependent for tax purposes.

5. Medical expenses. The disallowance equal to 7.5% of adjusted gross income is a high hurdle, but those who qualify shouldn't overlook all possible expenses, listed in IRS publication 502. Ms. Labant advises married couples to consider filing separately if one partner has high bills. "This is one of the only times that filing separately can lower the total tax bill," she says.

6. Sales-tax deduction in lieu of income taxes. This provision, which Congress has extended through 2011, allows itemized deductions for state and local sales tax instead of state and local income taxes. Taking this is a no-brainer in states without an income tax, and it may work for others if state income taxes are relatively low but a taxpayer had big-ticket purchases such as a car, boat or engagement ring, according to H&R Block's Tax Institute.

7. Moving expenses. Taxpayers who moved more than 50 miles for work and stayed employed may often deduct reasonable moving expenses. No itemization is necessary. See IRS publication 521.

8. Domestic Production Deduction. This generous benefit for having a qualified business in the U.S. can be claimed by sole proprietors, partnerships and corporations; it can even apply to farmers. It is easy to miss, says Chris Hesse, a CPA with LarsonAllen LLP in Minneapolis, "because no checks are written and tax-prep software may be unaware of it."

8 Audit Triggers

1. Mortgage-interest deduction over $50,000.Taxpayers are allowed to deduct interest on qualified loans up to $1 million (plus $100,000 of home-equity debt), and $50,000 is roughly equal to the annual interest on a $1 million loan at 5%. "Clients with larger payments are sometimes too busy to refinance," says David Lifson of Crowe Horwath CPAs in New York, "but they are likely to hear from the IRS."

2. Large charitable contributions, especially of noncash items. Taxpayers must have proof for every dollar of donation deductions, and sometimes appraisals. See IRS publications 526 and 561.

3. Schedule C business losses more than two years in a row. Because these losses are deductible against other income, losses in three or more consecutive years arouse the IRS's suspicion that they are nondeductible "hobby losses." A small profit raises taxes very little and diverts attention, says Robert Gard of Gard & LaFreniere, an Atlanta-area CPA firm.

4. Home-buyer tax credit. Congress has passed three versions of this stimulus since 2008, and research by official watchdogs showed substantial fraud in the initial one. Later versions require taxpayers to provide documents proving they qualify for the break.

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5. Rental real estate, especially with losses. A perennial red flag, especially if the taxpayer claims to be a real-estate professional, because the losses are then deductible against ordinary income. The IRS will be even more suspicious if the wages and professional activities are performed by a single person or one partner of a couple, because professional status often requires a 750 hour-a-year commitment, says James Guarino of Boston-area CPA firm Moody, Famiglietti & Andronico.

6. Payouts to subchapter S owners who earn little or no compensation. Owners of closely held businesses using subchapter S sometimes pay themselves in dividends and lowball their wages in order to minimize the 15.3% payroll tax. It's difficult for the IRS to police, but those who take too little compensation are asking for IRS attention, Mr. Gard says. One rule of thumb: The ratio of pay to profits should be 70% or higher.

7. Large deductions in relation to income, especially for business travel and entertainment. What is too large? That's hard to say, and the IRS zealously guards its audit formulas. See IRS publication 463.

8. Home office--maybe.Years ago, the IRS was famous for challenging home-office deductions, but has backed off lately, say some experts. See IRS publication 587.

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