How a Mortgage Works

A step-by-step guide to every stage of a mortgage -- from how your payment is calculated to how the loan is paid off over 15 or 30 years.

What a mortgage is

A mortgage is a loan used to purchase real estate where the property itself serves as collateral. The lender provides the purchase funds, and the borrower repays the loan plus interest through regular monthly payments over an agreed term -- typically 15 or 30 years. If the borrower stops making payments, the lender has the legal right to take ownership of the property through foreclosure. Because the loan is secured by real estate, mortgage rates are generally lower than unsecured debt like credit cards or personal loans.

The five components of a mortgage payment

Principal is the portion of your payment that reduces the loan balance. In early years, this is a small fraction of your payment. In later years, it becomes the dominant component.

Interest is the lender's compensation for providing the loan. It is calculated monthly as a percentage of your remaining balance. Your interest charge decreases each month as your balance falls.

Property taxes are collected monthly by your lender and held in escrow until the tax bill is due. The amount depends on your local tax rate and your home's assessed value.

Homeowners insurance is similarly collected monthly and held in escrow. It is required by lenders for the life of the loan to protect their collateral interest in the property.

PMI (private mortgage insurance) applies when your down payment is less than 20% of the purchase price. It protects the lender (not you) in case of default and is canceled by law when your loan balance reaches 78% of the original home value.

How your interest rate is determined

Mortgage rates reflect the cost of money in the broader economy, influenced primarily by the bond market -- specifically yields on 10-year U.S. Treasury notes. When Treasury yields rise, mortgage rates tend to follow. The Federal Reserve influences short-term rates through monetary policy, which affects mortgage rates indirectly. Beyond market rates, your individual rate is determined by your credit score, down payment size, loan type, property type, and the lender you choose. Borrowers with higher credit scores and larger down payments consistently receive lower rates.

How amortization works over 30 years

With a standard 30-year mortgage, you make 360 equal monthly payments. Early payments are primarily interest with very little principal reduction. Later payments are primarily principal. This structure means that homeowners who sell or refinance in the first few years of a loan have paid mostly interest and built little equity through paydown -- their equity comes almost entirely from their down payment and any home price appreciation.

On a $400,000 loan at 7% over 30 years, the monthly payment is approximately $2,661. Over the full term, you pay back the $400,000 you borrowed plus roughly $558,000 in interest -- a total of $958,000 for a $400,000 loan. This illustrates why mortgage rate shopping and making strategic extra payments can have such large financial impacts over time.

The mortgage approval process

Getting a mortgage involves three primary qualification factors. Your credit score determines the loan programs you can access and the rate you will be offered. Your debt-to-income ratio (DTI) determines how large a monthly payment you qualify for -- lenders typically limit housing costs to 28 to 31% of gross income and total debts to 43 to 45%. Your assets determine whether you have enough cash for the down payment, closing costs, and required reserves. Lenders verify all three through documentation: pay stubs, tax returns, bank statements, and employment verification.

Fixed-rate vs. adjustable-rate mortgages

A fixed-rate mortgage keeps the same interest rate for the entire loan term. Your principal and interest payment never changes, making budgeting predictable. A 30-year fixed is the most common mortgage type in the United States. An adjustable-rate mortgage (ARM) starts with a fixed rate for an initial period (typically 5, 7, or 10 years) and then adjusts annually based on a market index. ARMs offer lower initial rates but carry the risk of payment increases if rates rise during the adjustable period.

Closing costs and what to expect at closing

Closing costs are fees paid at the time of purchase to complete the mortgage transaction. They typically run 2 to 5% of the loan amount and include lender origination fees, title search, title insurance, appraisal, recording fees, prepaid interest, and escrow setup. You will receive a Loan Estimate within three business days of applying and a Closing Disclosure three days before closing -- both documents itemize every fee. Review them carefully and compare the final numbers to the estimate before signing.

Content is for educational purposes only and does not constitute financial, mortgage, legal, or tax advice. Consult a licensed mortgage professional before making any financing decision.