When it comes to buying a house, it's often the final expense involved -- mortgage closing costs -- that confuse and frustrate homebuyers most, even those accustomed to paying super-sized jumbo loans.

Although closing costs can represent between 2 percent and 4 percent of the total price of the home, many buyers don't understand what closing costs entail. Too many borrowers only inquire about the interest rate. They also should ask how much money closing the loan would cost and then ask several other lenders the same question, before they begin the actual loan process.

Once you've submitted a loan application, lenders by law must give you within three days a Good Faith Estimate, or GFE, of the closing costs. You should look at the GFE costs as carefully as you do the interest rate and monthly payment, and if something doesn't make sense, ask the lender for an explanation that does make sense.

Some lenders are willing to negotiate the closing costs, especially if these are fees they charge for their own services. And some lenders may offer lower closing costs or even eliminate them, in exchange for a higher interest rate. Sometimes you can get the seller to pay for some or all of the closing costs. But you should be aware that by the time you get to the actual closing, you are locked into all the fees on the list-even ones that you might not understand. So be sure to study them before you agree to the loan.

Let's break closing costs into types of fees and examine each one. Remember that the size of the total bill will vary depending upon where you live, the price of the house, the size of the loan, your lender, local taxes and fees, and on your agreement with the seller.

The borrower generally pays for two "up-front" fees. First is the credit check, a report that normally costs around $35 and shows how good your credit rating is. Second is the appraisal to prove to the lender that the house you want to buy really is worth what you are being asked to pay for it. Appraisal costs can vary depending upon location and the home's size, but you are normally talking about several hundred dollars.

Next come the lender fees, and these can vary from company to company. In a typical mortgage, the lender fees pay for the actual loan processing and paperwork and they can amount to several hundred dollars. Different lenders use different names for the fees, which are sometimes referred to as administration, processing, underwriting or application fees. You always should ask the lender exactly what the fees are, since some lenders will add extra fees, commonly called "junk fees."

Other fees folded into the lender's fees category could include the actual charge for preparing the myriad of loan documents that everyone involved in the transaction must sign or keep on file. They usually cost around $50. There also is a tax service fee that ranges from about $50 to $75. It pays an outside company that determines exactly what taxes must be paid on the property involved and ensures that they are paid properly. There is also a $25 fee for a flood check, sometimes called flood certification, to determine if the property is on a designated high-risk flood plain. If it is, national flood insurance becomes an issue.

The title search guarantees that the person selling the property has clear title to it. Lenders want title insurance, which is usually purchased by the buyer. Title insurance means that if there has been a mistake, or if someone files a lawsuit claiming to be the actual owner, the lender is covered. Buyers can also purchase title insurance to provide themselves with this type of protection. This can be relatively expensive, depending upon the property, where it is located, the number of previous owners or the number of liens that have been filed against it. But if there is a mistake that comes to light after you buy the house, defending and resolving any claim that arises is the insurance company's problem.

If you live in a state that uses an escrow company, there will be an escrow fee. If you use a real estate attorney, he or she will charge a similar fee for putting together all the paperwork that goes into a purchase or sale. Part of the job-whether an escrow company or a real estate lawyer does it-is to make sure that everyone sees, gets, and has everything they must have, exactly when they need it. The escrow company also handles the money and channels funds to the right people when the papers are finally signed. This service normally costs several hundred dollars. The escrow company or attorney also makes sure that the new deed is filed and registered with the appropriate jurisdiction(s) and that the fees, which vary according to location, are paid to record that filing.

Closing costs also can include accrued interest on the old loan, pre-paid interest on the new one, and any property taxes, insurance, or fees and assessments that are due immediately. While most mortgage payments include property taxes, insurance and fees or assessments, these do not get paid until the first mortgage payment is made, so a portion must be paid up front.

Even though closing costs amount to only a fraction of the total cost of the house, they can cause an inordinate amount of frustration and confusion. Get a clear understanding of exactly what your closing costs will be, and do some negotiating before you agree to accept the loan or buy the home. That way the final closing might cause a sore hand from having to sign so many different forms, but it should not cause a sore temper. After all, once the papers are all signed, you should celebrate your new home, not stew about the costs of making it yours.