Complete the Personal Allowances Worksheet to determine the number of allowances to claim, figuring as if you had only one job, and enter the result on line 1 of the Two-Earners/Multiple Jobs Worksheet.
Use Table 1 beneath the Two-Earners/Multiple Jobs Worksheet to find the number to enter on line 2, based on your lowest-paying job and your filing status. For example, in 2011 if you are single and your lowest-paying job brings in $20,000, enter 2.
Subtract the amount on line 2 from the allowances on line 1. If the amount is 0 or greater, that is the number of allowances to claim. For example, if you are entitled to 3 allowances and have "2" from the table, you should claim 1 allowance. However, if you were only able to claim 1 allowance, your answer would be -1, which means you need to continue completing the Two-Earners/Multiple Jobs Worksheet.
Multiply the absolute value of the negative number from Step 3 by the appropriate number from Table 2 at the bottom of the Two-Earners/Multiple Jobs Worksheet. In this example, if you are single and your highest-paying job pays $80,000, multiply 1 by $930 to get $930.
Divide the Step 4 result by the number of pay periods left in the year to find out the additional amount your employer should withhold each pay period. In this example, if you are paid monthly and have five months remaining in the year, divide $930 by 5 to find you need an additional $186 withheld from your highest-paying job. Report this amount on line 6 of your W-4 for your highest-paying job.