The ease of the one-page 1040EZ is appealing, but it limits the number of ways to save on your tax bill.

This shortest personal return restricts filers to claiming just one credit: the earned income tax credit, or EITC, a tax break designed to help out individuals who don't make much money. And even how you collect the EITC can determine whether you can file the EZ. If you got advance payment of the earned income credit during the year through your employer, then you can't use this easiest of returns; you'll have to file the long 1040 or 1040A.

You also need to look at those other two individual tax returns to take advantage of additional income adjustments and tax credits.

Form 1040A
The 1040A form is the next step up the tax-form ladder. As with the EZ form, the earning limit on filers wanting to use the 1040A has increased, so more taxpayers should be able to use it.

Individuals choosing the 1040A can file using any of the five available filing status options: single, married filing jointly or separately, qualifying widow or widower, or head of household. 1040A filers also can claim, in addition to the EITC, several tax credits -- the child, additional child, education, dependent care, elderly or disabled and retirement savings credits -- that are not available with the EZ.

You also can file Form 1040A if:

• Your taxable income, or combined incomes, is below $100,000.
• You have capital gain distributions, but no other capital gains or losses.
• You do not itemize deductions.
• The only adjustments to your income are from deductible IRA contributions, student loan interest payments, penalties on early withdrawal of savings or you handed over your jury duty pay to your employer.

Form 1040A also gives you the chance to claim several adjustments to income. These items are sometimes referred to as above-the-line deductions, because you claim them just before the bottom line of the form, the one where you enter your adjusted gross income. By reducing your total gross income, your taxable income will be lower and your tax bill should be smaller, too.

Adjustments allowed on Form 1040A include educator expenses, certain IRA contributions, student loan interest and some college tuition and fees.

Form 1040
Finally, choose Form 1040 if your earnings are larger, you itemize deductions or you have more complex investments and other income to report. This usually means added tax paperwork needs to be filed, too.

Additional paperwork also is associated with the many tax credits that show up only on the long 1040. The extra work, however, is offset by the added savings these credits, such as the one for taxes you paid to a foreign country or the one that helps cover some adoption costs, can produce for 1040 filers.

The longest return also offers more than a dozen above-the-line deductions that you can claim directly on the form itself (versus the four adjustments found on the 1040A). These allow you to reduce your gross income, thereby reducing the amount of income that's ultimately taxed. The adjustments include, among other things, breaks for alimony payments you made, self-employment taxes you paid or moving expenses you incurred.

These income deductions are found at the bottom of the 1040's front page, meaning you don't have to hassle with Schedule A and its itemizing limits. You will, however, have to fill out an additional form or schedule to claim a couple of these breaks.

You should file Form 1040 if:

• Your income or combined incomes for joint filers totals more than $100,000.
• You itemize deductions.
• You have self-employment income.
• You received income from the sale of property.

The "Which form should I use?" section of IRS Publication 17 has more details, examples and special circumstances requiring additional forms.

And just because you got a particular income tax form in the mail from the IRS doesn't mean you have to use it. The agency sends out forms based on your previous year's tax filing. If your situation has changed -- say, you now have enough deductions to make itemizing worthwhile -- then file a different form.

It could be tax money in your pocket.

Freelance writer Kay Bell writes Bankrate's tax stories from her Austin, Texas, home. She also writes two tax blogs, Bankrate's Eye on the IRS, and Don't Mess With Taxes.