My wife earns income throughout the year but refuses to have taxes taken out or make quarterly estimated tax payments. When combined with my appropriately taxed income on our year-end joint return, her untaxed income results in a sizable tax-due as well as an underpayment penalty. She offers to contribute, but refuses to pay the additional tax as established by her income, our filing status (MFJ), and our combined deductions and credits. She argues that her tax bill should be based on the lowest tax rate available - HH. :confused: If the additional tax due were a few hundred bucks, I'd suck it up and pay the tax on her income just to avoid the annual arguments. Unfortunately, the amount in question is significant - several thousand dollars. :eek: So I ask... if my approach to determining tax due on her income is flawed - as she says it is, what is a reasonable strategy?