What Is a Mortgage? Types, How It Works, and Examples

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A mortgage is a loan used to buy or refinance real estate in which the property itself secures the debt. The borrower receives money to purchase a home, land or other property and agrees to repay it, with interest, over a set term. In return, the lender gets a legal claim (a lien) on the property. If the borrower stops paying, the lender can foreclose: take the property through a legal process and sell it to recover what is owed. That security arrangement is what separates a mortgage from an unsecured loan. It is also why mortgages can be large and long, often 15 or 30 years.

How a Mortgage Works

Few buyers can pay the full price of a house in cash. The buyer pays part of the price up front as a down payment, and the lender funds the rest. The amount borrowed is the principal. The lender charges interest on the outstanding principal at an annual rate.

Most traditional mortgages are fully amortized. On a fixed-rate loan the borrower makes the same scheduled payment each month, and the final payment clears both principal and interest. What changes is the split. Early on, the large balance means most of the payment goes to interest. As the balance falls, more of each payment reduces principal. After the last payment, the lien is released and the borrower owns the property free and clear.

The legal side runs alongside the financial side. When the loan closes, the borrower signs two kinds of documents:

• A promissory note, which is the borrower’s promise to repay the debt on stated terms.
• A mortgage (or, in many U.S. states, a deed of trust), which pledges the property as security for that promise and is recorded in public land records.

If the borrower defaults, the security instrument gives the lender the right to foreclose. The lender, or a trustee under a deed of trust, can force a sale, use the proceeds to pay off the debt and have the occupants removed. Procedures, timelines and borrower protections are set by state law and vary by state.

The amortization formula

The level monthly payment on a fully amortizing fixed-rate mortgage comes from a standard formula:

M = P × [r(1 + r)^n] / [(1 + r)^n − 1]

Where:

• M = monthly principal and interest payment
• P = loan principal
• r = monthly interest rate (annual rate ÷ 12)
• n = number of monthly payments (years × 12)

The formula covers principal and interest only. Taxes, insurance and other charges are added separately.

Example of a Mortgage

Assumptions (hypothetical, not a quote or a typical market rate): a $400,000 home, a 20% down payment of $80,000, a loan of $320,000, a fixed annual interest rate of 6%, a 30-year term, and no points or fees.

• Monthly rate r = 0.06 ÷ 12 = 0.005
• Number of payments n = 30 × 12 = 360
• Monthly principal and interest: about $1,918.56

In the first month, interest is $320,000 × 0.005 = $1,600. That leaves only about $318.56 to reduce the balance. Over 360 payments the borrower pays roughly $690,680 in total, of which about $370,680 is interest.

Now change one input. Keep the same $320,000 and the same 6% rate (an assumption for comparison; in practice, lenders often price 15-year and 30-year loans differently), but shorten the term to 15 years (n = 180):

• Monthly principal and interest: about $2,700.34
• Total paid: about $486,060
• Total interest: about $166,060

The shorter term raises the monthly payment by roughly $780 but cuts total interest by more than half. The balance shrinks faster, so interest accrues on a smaller amount each month.

What the monthly payment actually includes

The figure from the formula is rarely the full amount a homeowner sends each month. Lenders and loan servicers often set up an escrow account and collect extra money with each payment to cover:

• Property taxes charged by local governments
• Homeowners insurance premiums
• Mortgage insurance, if required (see below)
• In some cases, other charges tied to the property

These items are often abbreviated as PITI: principal, interest, taxes and insurance. Because taxes and insurance premiums can change from year to year, an escrowed payment can change even on a fixed-rate loan.

On a conventional loan with less than 20% down, the lender may require private mortgage insurance (PMI). PMI protects the lender, not the borrower, if the loan defaults, and it adds another monthly cost. In the hypothetical above, the 20% down payment would generally avoid that requirement on a conventional loan.

The Mortgage Process

Getting a mortgage follows a fairly consistent sequence, though details differ by lender and loan program.

1. Application. The borrower applies with one or more lenders. Applying with several allows offers to be compared.
2. Documentation. The lender asks for evidence of ability to repay, typically bank and investment statements, recent tax returns, pay stubs and proof of employment.
3. Credit check. The borrower’s credit report and score affect both approval and the rate offered.
4. Pre-approval. Many buyers seek pre-approval while house hunting. The lender indicates how much it will lend and at roughly what rate, subject to final verification. This shows sellers that an offer is backed by financing.
5. Underwriting. After a purchase contract is signed, the underwriter verifies income, assets, debts and the property. This usually includes an appraisal to confirm the home’s value supports the loan.
6. Closing. The buyer pays the down payment and closing costs and signs the note and security instrument. The seller transfers ownership and receives the proceeds. The lender may charge origination fees, sometimes as points.

Mortgages are available from banks, credit unions, savings institutions, mortgage-only companies and online lenders. Nonbank lenders now account for a large share of the market. A mortgage broker does not lend its own money but shops a borrower’s application among multiple lenders.

Types of Mortgages

Mortgages differ mainly in how the interest rate behaves, how the principal is repaid, how long the term runs and who backs the loan. The 30-year and 15-year fixed-rate mortgages are the most widely used. Terms can be as short as five years or as long as 40 years or more.

Fixed-rate mortgages

The interest rate is set at closing and does not change for the life of the loan, so the principal and interest payment stays the same from the first month to the last. This predictability is the main appeal. The trade-off is that the borrower does not benefit if market rates fall, except by refinancing into a new loan.

Adjustable-rate mortgages (ARMs)

An ARM has a fixed rate for an initial period, after which the rate resets periodically based on a benchmark index plus a margin set in the loan contract. The initial rate is often lower than a comparable fixed rate, which makes early payments more affordable. After the fixed period, the payment can rise if market rates have gone up.

ARMs are described by their structure. A 5/1 ARM keeps the rate fixed for five years and then adjusts once a year. Most ARMs include caps that limit how much the rate can rise at the first adjustment, at each later adjustment and over the life of the loan. Plugging the maximum capped rate into the amortization formula shows the highest possible payment.

Government-backed loans

Some mortgages are insured or guaranteed by federal agencies, which allows lenders to approve borrowers who might not meet conventional requirements for income, credit or down payment:

• FHA loans, insured by the Federal Housing Administration, allow lower down payments and more flexible credit standards, with mortgage insurance premiums built in.
• VA loans, guaranteed by the U.S. Department of Veterans Affairs, serve eligible service members, veterans and certain surviving spouses.
• USDA loans, backed by the U.S. Department of Agriculture, serve eligible borrowers buying in qualifying rural areas.

A mortgage that is not insured or guaranteed by a government agency is called a conventional loan.

Interest-only and payment-option loans

With an interest-only mortgage, the borrower pays only interest for a set period, so the balance does not shrink. Afterward, payments jump to cover principal over the remaining term, or a large balloon payment comes due. Payment-option ARMs let borrowers choose payments that may not cover the interest due, so the balance can grow. These structures are complex and less common. Many borrowers got into trouble with them during the early-2000s housing bubble, when payments reset higher and home values fell.

Reverse mortgages

A reverse mortgage works in the opposite direction from a purchase loan. It lets homeowners aged 62 or older borrow against their home equity, received as a lump sum, fixed monthly payments or a line of credit. The borrower makes no monthly loan payments. Interest and fees are added to the balance, which becomes due when the borrower dies, sells the home or moves out permanently. The borrower must still pay property taxes, insurance and maintenance.

Second mortgages and home equity loans

A home can carry more than one mortgage. The first mortgage has the senior claim. A second mortgage, commonly a home equity loan or home equity line of credit (HELOC), is a junior lien paid from foreclosure proceeds only after the first. There is no fixed legal limit on junior mortgages, but each depends on sufficient equity, an acceptable debt-to-income ratio and an adequate credit score.

What Lenders Look At

Lenders approve loans through underwriting, which weighs the borrower’s ability and likelihood to repay against the value of the collateral. The main factors are:

• Credit score and history. A higher score generally qualifies for a lower rate. Riskier borrowers pay higher rates.
• Debt-to-income (DTI) ratio. Monthly debt payments, including the proposed mortgage, divided by gross monthly income.
• Down payment and loan-to-value. The loan-to-value (LTV) ratio compares the loan amount with the property’s appraised value. In the example above, a $320,000 loan on a $400,000 home is an LTV of 80%. Higher LTV means less borrower equity and more risk to the lender, which can mean a higher rate or required mortgage insurance.
• Income and employment stability. Documented, ongoing income to cover payments.
• Assets and reserves. Savings available after closing.

Mortgage lending discrimination is illegal in the United States. The Fair Housing Act and the Equal Credit Opportunity Act bar lenders from denying credit or setting terms based on race, color, religion, national origin, sex, marital status, age, disability, receipt of public assistance or other protected characteristics. Complaints can be filed with the Consumer Financial Protection Bureau (CFPB) or the U.S. Department of Housing and Urban Development (HUD).

How to Compare Mortgage Offers

The interest rate is the headline number but not the whole cost. The price of a mortgage also depends on the loan type, the term, any discount points and market rates when the rate is locked. Rates differ by lender and change frequently, so compare several offers on the same day.

Discount points are an upfront fee paid at closing to buy a lower rate for the life of the loan. They pay off only if the borrower keeps the loan long enough for the monthly savings to exceed the cost. Offers should be compared with the same number of points.

The annual percentage rate (APR) helps here. It folds the interest rate together with certain fees and points into a single annual figure, so two loans with the same rate but different fees show different APRs. When comparing offers, look at:

• Interest rate and APR
• Points and lender fees
• Fixed versus adjustable rate, and for ARMs, the adjustment schedule and caps
• Term length and its effect on total interest
• Mortgage insurance requirements
• Any prepayment penalty
• Estimated escrow for taxes and insurance

Distinctions Readers Often Confuse

Owning the home vs. owning the debt. A borrower with a mortgage owns the property. The lender holds a lien, a claim on it, not title to it in the ordinary sense. Ownership is only at risk if the borrower defaults and the lender completes a foreclosure.

Mortgage vs. deed of trust. Both secure a home loan. A mortgage involves two parties, borrower and lender. A deed of trust adds a third party, a trustee, who holds legal title for the lender’s benefit. Which instrument is used depends on state law, and it can affect whether foreclosure goes through the courts.

Limitations and Risks of a Mortgage

• Total interest cost. On a 30-year loan, interest can approach or exceed the original principal.
• Foreclosure risk. Because the home is collateral, prolonged missed payments can cost the borrower the property and damage their credit.
• Payment shock. ARMs, interest-only loans and balloon structures can produce sharply higher payments after the initial period.
• Negative equity. If home values fall, the borrower can owe more than the property is worth, which makes selling or refinancing difficult.
• Ongoing ownership costs. Taxes, insurance and maintenance continue for as long as the borrower owns the home, and escrowed amounts can rise.
• Rate exposure at the time of borrowing. A fixed rate locks in the rate available at closing. The 30-year fixed average fell to its lowest levels in about 50 years during 2020 and 2021, then climbed above 7% in October 2022 for the first time in roughly two decades.

Why Is It Called a Mortgage?

The word comes from Old French, by way of English law: mort (dead) and gage (pledge), so a “dead pledge.” The pledge “dies” in one of two ways. Either the debt is repaid and the lender’s claim on the property ends, or the borrower defaults and the property is lost to the lender.

FAQs

The Bottom Line

Home buyers and owners weighing a loan should judge it by total cost, not the rate alone. The term, points, fees, mortgage insurance and escrow for taxes and insurance all shape what the borrower pays, and APR helps compare offers with different fees. Comparing several lenders on the same day, and checking ARM caps for the highest possible payment, gives a clearer picture of the real commitment.