Purpose of Loan: Loan will be used to purchase or refinance a home that the borrower intends as a permanent residence. Loans to purchase second (vacation) homes, or properties to be held as an investment, will be priced higher. Refinancing to raise cash, termed "cash-out refinancing," is also priced higher.

Occupancy: All co-borrowers intend to occupy the property. If one of them does not, it is a negative that could raise the price.

Lien: The loan has a first lien against the property and there are no other liens. Second liens are priced higher, and a first lien on a property with a second lien on it might also be priced higher.

Property Type: The property is a detached single-family home. Loans secured by two-, three- and four-family homes, by attached homes ("duplex," "triplex" or "row"), or by manufactured (factory-built) homes, could be priced higher. So may units in condominiums, cooperatives or planned-unit developments.

Term (on Fixed-Rate Loans): The loan has a 15-year term. Prices of 30-year loans are higher, and 40-year loans are priced higher yet. Twenty- and 25-year loans are typically priced between 15s and 30s. Ten-year loans, if available, are likely to be priced like 15s, or slightly lower.

Down Payment: The borrower will put 20 percent down, or more. Smaller down payments result in either mortgage insurance or a higher interest rate. The following categories are widely used in pricing: 20 percent and over, 15 percent-19.9 percent, 10 percent-14.9 percent, 5 percent-9.9 percent, 3 percent-4.99 percent, 0 percent, -5 percent, -7 percent. A negative down payment means that the loan amount exceeds the property value.

Loan Size: The loan is smaller than the maximum eligible for purchase by Fannie Mae and Freddie Mac, which was $359,650 in 2005, but not too much smaller. Since it costs lenders as many dollars to originate a small loan as a large one, loans below some threshold, often $50,000 or so, will be priced higher. Loans larger than $359,650, called "jumbos," are also priced higher because they can't be sold to the agencies.

Required Lock Period: The borrower intends to close the loan shortly and therefore needs to lock the terms of the loan for only 15 days. Common lock periods are 30, 45, 60, 75, 90 and 120 days. The longer the period, the higher the price.

Escrow of tax and insurance payments: The borrower agrees to maintain an escrow account with the lender, who will pay taxes and insurance as they come due. Borrowers who opt to avoid escrow will pay more.

Standard Documentation: The borrower's income and assets will be verified by the borrower's employer and bank. Other forms of documentation will be priced higher, depending on the form. These range from minor deviations from the standard, as when the borrower wants to submit pay stubs and bank statements; to stated documentation where the lender accepts what the borrower tells him; to no documentation at all. The larger the deviation from standard documentation, the higher the price.

Credit Score: The borrower has a credit score equal to or above the score required by the lender on the specified type of loan. Borrowers with scores below the required score will pay more. The required scores usually run from 720 to 740 (out of a possible 850), but I have seen them as low as 680 and as high as 780.

Prepayment Penalty: The borrower will accept a prepayment penalty. Borrowers who don't accept a penalty will pay a higher price. Borrowers with low credit scores, however, may find that a penalty is a requirement of their loan.

Expense-to-Income Ratio: The ratio of total housing expense to borrower income is below the maximum for the loan program. Higher ratios may raise the price.

How much any deviation from the optimum package of features will cost you usually depends on the other features of your package. If you have good credit in particular, deviations from the optimum package will cost much less than if your credit is shaky.