I have some extra cash each month after Maxing out my T401k. Would it be better to use the Credit Card/ Target red card trick to pay off my mortgage (3.5% interest + anywhere from 2-5% cash back using the trick), or use the extra money to start contributing to a Roth IRA? I feel like the ROI is currently better paying off the mortgage rather than the Roth, but you wiser, longer mustachians may have a different idea!
