Lower Tax Liability
Filing a joint return as a married couple may allow you and your spouse to lower your tax liability and secure a larger return, according to Internal Revenue Service Publication 501. Your tax liability is lower because you and your spouse combine your income onto one return while increasing your allowable deduction amounts. Filing a joint return can also pull you and your spouse's income into a lower income tax bracket resulting in a lower tax rate. This is especially true if the annual income of you and your spouse is vastly different, according to Turbo Tax's website.
Married Filing Separately
Filing your taxes separately while married usually results in higher tax liability, according to the IRS. This is because the IRS assesses your and your spouse's income at a higher tax rate than would be the case if you filed a joint return. Filing a separate return also lowers the amount of deductions you can claim for dependent child care assistance and eliminates you and your spouse's ability to claim certain tax credits including the Earned Income Credit for low-income earners and the American Opportunity Credit for education-related expenses.
Filing Taxes as Single
The amount of tax refund you can receive when filing as single depends greatly on your income and the number of exemptions you can claim. As a single taxpayer, you have lower available tax deductions than a married couple filing a joint return, but you're also only responsible for reporting your own income.
Claiming a dependent child on your federal tax return can generate a significant tax refund if you're filing as a married couple or filing as a single taxpayer. As of 2010, you may use a deduction of up to $3,000 for one dependent child if you're filing your taxes as single and up to $6,000 if you're a married couple filing jointly. This means a single taxpayer with a dependent child can secure a much higher refund than a single taxpayer without a child. This is also the case for married couples filing jointly.