Nonresident VT tax

Vermont requires that you use the same filing status as your federal return except for married couples where one spouse is a Vermont resident and the other spouse is a nonresident. Since you're both nonresidents, you wouldn't meet the exception, so you would have to file jointly with your wife unless you file separately for federal purposes.

You can compare how your tax changes when choosing Married Filing Jointly versus Separately by following the instructions in this support article. 

Q. Would I owe less in Vermont state tax if I filed married filing separately on my VT tax form?

A. No. VT will not tax her income on a joint state return.  In the TurboTax (TT) state interview, you will be asked to identify each piece of income as VT or not VT.  Although it may appear, at the beginning of the form,  that VT is taxing all you income, at the end a percentage is applied so that only your VT  income is taxed.