How to Calculate How My Taxes Will Change if Married Jointly
- 1). Obtain three federal 1040 income tax return forms, plus the 1040 instruction booklet for the year you wish to analyze. Forms and instructions are available on the IRS website (see References).
- 2). Prepare your federal 1040 income tax return through Line 43, taxable income. You must prepare three separate 1040 forms through Line 43. Use your income and deduction information on one form to figure your taxable income separately. On a new form, use your spouse’s income and deduction information to figure his separate taxable income separately. On the third form, combine the income and deduction information for each of you to figure your joint taxable income.
- 3). Locate the tax tables in the instructions for Form 1040. Use the married filing separately tax table and match your separate taxable income to the table amounts. The amount shown is your income tax if you file a separate return. Match the taxable income from your spouse’s tax return to the married filing separately table. Match your joint taxable income to the married filing joint tax table. The amount shown is your tax when you file a joint return.
- 4). Look at your income tax documents, and calculate the total federal income tax withheld from your income. List the amount withheld for yourself and the amount withheld for your spouse on your separate returns on Line 61. Combine the two amounts, and record your joint withholding on Line 61 of your joint return. If you are eligible for additional tax credits separately or jointly, calculate the credits and report them on the appropriate return.
- 5). Subtract withholding credits from the taxable income of each return. Look at the results for each of the three returns to determine which method produces the lowest tax liability or the highest tax refund. In some cases, it is more advantageous to file separate returns, and in other cases it is more advantageous to file a joint return.
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