How can I determine the percentage of Federal taxes due that are owed by me versus the percentage owed by my wife?

[Steve-Ess]

I am an employee, but my wife is self-employed. We file jointly but generally keep finances separate.

[KatherineC · Accepted solution]

The self-employment taxes on Line 57 of your Form 1040 would all belong to your wife. 

If all other income amounts (other than your W-2 and your wife's self-employment income - Schedule C) are joint income you could calculate your respective income tax amounts as follows:

Add your W-2 income and your wife's self-employment income for the total earned income. 

Divide your W-2 income by the total earned income and multiply by (the total taxes less the self-employment tax) would equal your share of the Federal taxes.

Divide your wife's self-employment income by the total earned income and multiply by (the total taxes less the self-employment tax), plus the Self-Employment tax equals your wife's share of the Federal taxes.