Pay the 20% to Fed and generally 5% to state. The 20% to Fed is to cover both your income tax and self-employment tax. Self-employment tax is 15.3% of your net income and is for Social Security and Medicare taxes. The 5% to state is really dependent on your state income tax rates. This is a ballpark estimate that you can changed depending your state of residence. Another option is to have your wife withhold more tax from her pay to cover the amount of additional tax on you self employment income. Then you would not need to pay estimates, if you file a joint return.
