Look for an amortization table calculator. That will give you the run down on payments/interest. The tax amount is the interest paid.

Typically though, the amount of interest paid on the loan will be equal to, if not greater than, the original amount of the loan. Add the closing costs to it as well and that is the total cost of the loan.

Ex: a $120k note financed at 6% over 30 years would have a P/I payment of 719.49. Total interest paid over 30 years, $139k.

Figure closing costs of 6k. Total cost for a 120k loan is $145k.

If you make $1k/mo payments, loan will be paid off in about 15.3 years and only pay about $64k in interest. Total cost: $70k. Savings of $75k. That is money in their pocket, not money that is taken off at the end of the year (which would at the 35% bracket, only save about $25k in taxes spread out OVER the additional 15 years).

Note: I am not a tax person so that number is an estimate.