I've owned my place for 8 years, my mortgage was refinanced through HARP @4% from 5.875% (shitty BOA mortgage) a few years ago effectively lowering my monthly without changing my payoff date.

Discover Financial wants to offer me a slightly lower rate, 3.75% but at 30 years. It would drop my payment about $400-$500 a month. I don't plan on living in this home for 30 years, so should I do it? Or do I never want to "reset" the years on the mortgage just to lower the payment. Because then I'm basically paying mostly interest in the first few years again.

I'm new to this for the most part so I thought I'd ask the veterans here.

 

What you need is a mortgage calculator spreadsheet. Free Home Mortgage Calculator for Excel

Create a spreadsheet for your current mortgage, then create another spreadsheet for the new proposed mortgage. You can then take a look at what the balances for each mortgage will look like say 5-10 years from now. With this information you can then make a decision for your particular situation.

The spreadsheet is pretty useful, you can run all kinds of simulations on it (extra payments). I suggest you run one for a 15 year mortgage and look at the difference of how much of your payment goes to interest.

 

Thanks!

 

How much longer do you plan to live there?
As doopstr said look at 15 and 20yr mortgages. A 30 year, as you said will basically put you back to paying mostly interest.

Now if you do go 30yr try to continue paying the amount you are paying currently. That will reduce the principal significantly.