Q. We've had a mortgage for several years and I was recently appalled at how much of our payment goes toward the interest on this home and how little goes toward our balance. Is there a way to reverse the funds to pay off the principal? Homes in Michigan are not selling and the market value is extremely low. I fear we will end up selling the house for less than we owe.

A.There's no way to change the basic rules of borrowing.

Most consumer loans require you to pay the interest on their balance each month. Only then is any additional money applied to paying off your debt.

So consider a $100,000 mortgage at 6.3% annual interest for 30 years. The monthly payment will always be $618 a month for principal and interest.

For the first month, $525 goes to pay your interest and the remaining $93 is applied against your debt. With each passing month, the portion going to interest falls a little and the portion applied to reducing the principal increases.

After 19 years, the amount is split almost equally between principal and interest, and for the last 11 years of the loan more than half of what you pay goes towards reducing the principal.

Our mortgage calculator will show exactly how much you'll pay in interest and principal each month. Just fill in the amount and terms and click "Show Amortization Table."

We sympathize with everyone who has to cope with falling home values and the possibility that they now owe more than their homes are worth.

But if you try and sell your home for less than you owe on your mortgage, your lender will expect you to bring a check to the closing to make up the difference.

For example, if your balance is $150,000 and you strike a deal to sell the home for $140,000, you'll have to give all of that to the bank or mortgage company along with another $10,000 from your savings.

If you don't, the lender will refuse to release the title to the home and you won't be able to sell it.

If you don't have enough money for that, you can ask it to accept a short sale, which is where the lender agrees in advance to write-off the difference between what you owe and the sales price.

Most lenders are reluctant to do that unless the homeowner is suffering through a serious financial crisis, such as a layoff, illness or divorce, and can no longer afford the payments.

Expect your lender to resist such a request if your income hasn't been dramatically reduced and you simply want to move in during a difficult time in the housing market.

A short sale will also go on your credit report as a bad debt. But it's still a smart move if default and foreclosure is the only other option.