First, what is a point? It's another way for a lender to make money - another loan fee. They are sometimes called discount points - you pay them to get a discounted interest rate on your loan. It is also said that you are "buying down" the interest rate by paying points. But the simplest definition is that a point is one percent of the loan amount. Therefore, for example, two points on a $200,000 loan would be two percent, or $4,000.

To some extent, whether you should pay the points depends on your job,your interests and all the things that predict your future. Points, you see, are paid up front, while your savings from the lower interest rate are spread out into the future. Obviously then, you get more benefit if you own your home longer, or if you don't refinance for a long time.

Let's look at an example. Borrow $250,000, without points, at 6% on a 30-year mortgage, and your payment would be $1,499 per month. Pay two points, or $5,000, to get the interest rate down to 5.5%, and your payment on the $255,000 (points are often added on to the loan), would be $1,448 per month. You save $51 per month.

It will take almost eight years to save the $5,000 you paid in points. To calculate this, divide the cost of the points by the monthly savings to determine how many months it takes to pay back the cost. If you plan to keep the mortgage loan for longer than that it can be worthwhile to pay points. It can get more complicated. For example, invest $5,000 and use it each month to pay the extra $51, and it will certainly last more than eight years.

Just avoid the complex computations. Use the rough and simple formula above. It is accurate enough, given how unpredictable life is. Simply ask if you're likely to keep the loan for eight years - or whatever length of time it takes to repay the cost of the points. Will you move before that, or will you likely refinance within that time frame? If so, skip the points.

Is there a circumstance when you should pay the mortgage points without regard to how long you'll keep the loan? Yes - when your offer on a home makes the seller pay those loan points. Do a little math for this - it is worth a lot.

For example, if your offer states, "seller to pay up to $5,000 of buyers closing costs, including mortgage points," start by determining what non-loan costs the seller will be paying. Ask the real estate agent for help with this if needed. If these costs add up to $2,000 total, you have $3,000 more in costs he could be paying. In that case, if you are borrowing $200,000, you would want to pay 1.5 points to "buy down" the interest rate. The mortgage points would be $3,000 - paid by the seller at closing, along with the other $2,000 in costs. He has to pay up to $5,000, so if you don't pay points, it's like giving him a $3,000 gift (it's in the contract, after all).