You are able to claim the $7,500 electric vehicle tax credit to the extent that you have a federal tax liability regardless of what type of income generated that tax liability. Converting a portion of your traditional IRA to a Roth IRA would be one way to generate a tax liability in order to use the electric vehicle tax credit. If you live in a state that imposes an income tax, be sure to consider whether the Roth IRA conversion will generate state tax due.