My husband and I own 2 investment properties as well as our principal residence. We're in the process of refinancing one of them and my question is which debt should I pay down with the money? We have an unsecured line of credit that was used to fund the renovations. Normally the answer would be easy and I would pay that one down, however we use the interest against our income from the property to reduce taxes. So should I use it to pay down the mortgage on our principal residence, since we don't use that interest as a write off? The difference on the two rates is 1.85% if that helps at all.