Mortgages: the basics

The residential mortgage is the largest single financial obligation most U.S. households take on, the most precisely regulated consumer credit product, and the principal mechanism through which U.S. households build wealth. It is also legally and operationally complex: the loan a borrower signs at closing is typically originated by one institution, sold within weeks to a different investor, and serviced by yet another company, all under a disclosure regime that took its current form only in 2015 with the integrated TRID rules.

This article describes the principal structural variants of U.S. residential mortgages, the difference between origination and servicing, the role of the secondary market dominated by Fannie Mae and Freddie Mac, the function of escrow, and the integrated disclosure regime. It is a basics article; the longer treatment of specific products and processes would be substantially larger.

The principal product categories

Fixed-rate versus adjustable-rate. A fixed-rate mortgage carries a single interest rate for the entire term, typically 15 or 30 years; the monthly payment of principal and interest is constant over the term. An adjustable-rate mortgage (ARM) carries an initial fixed rate for a defined period (5, 7, or 10 years are common), after which the rate adjusts periodically based on an index plus a margin. ARMs typically have caps on per-adjustment and lifetime rate changes. Fixed-rate mortgages have dominated U.S. residential lending for the past several decades, particularly since the 2008–2009 crisis.

Conforming versus jumbo. A conforming mortgage is one that meets the size and underwriting standards set by the Federal Housing Finance Agency for purchase by Fannie Mae or Freddie Mac. The conforming loan limit is adjusted annually; for 2025, the baseline conforming limit was $806,500, with higher limits in defined high-cost areas (verify against the FHFA's most recent figures). A jumbo mortgage is one above the conforming limit; it cannot be sold to Fannie or Freddie, so it is either held on the originating institution's balance sheet or sold through private channels. Jumbo mortgages historically carried higher rates than conforming, though the spread varies.

Conventional versus government-backed. Conventional mortgages are those not insured or guaranteed by a federal agency. Government-backed mortgages include FHA loans (insured by the Federal Housing Administration, with lower down-payment requirements and broader credit eligibility), VA loans (guaranteed by the Department of Veterans Affairs for eligible veterans and active-duty service members), and USDA loans (guaranteed by the Department of Agriculture for rural-area borrowers). Each of the government-backed programs has its own eligibility, fee structure, and underwriting rules.

Origination, servicing, and the secondary market

A mortgage involves several distinct functions that may or may not be performed by the same institution.

Origination: the process of taking the application, verifying the borrower's eligibility, underwriting the loan, and closing. The originator is the lender of record at closing — the entity named on the note and the mortgage. Originators include banks, credit unions, and non-bank mortgage lenders; non-bank originators have grown to account for the majority of U.S. residential mortgage originations in recent years.

Secondary market sale: most originated mortgages are sold within weeks of origination to a secondary-market investor. The principal investors are Fannie Mae and Freddie Mac (which purchase conforming mortgages and package them into agency mortgage-backed securities), Ginnie Mae (which guarantees securities backed by FHA, VA, and USDA loans), and private investors (which buy jumbo and non-agency loans). The sale converts an illiquid loan into cash that the originator can use to make more loans; from the borrower's standpoint, the sale typically does not change the loan terms.

Servicing: the ongoing administration of the loan — collecting monthly payments, managing the escrow account, handling delinquency and loss mitigation, providing year-end tax statements, processing payoffs. The servicer may be the originator, a separate company that purchased servicing rights from the originator, or a sub-servicer hired by the investor. The mortgage servicer is the company the borrower interacts with after closing; the entity actually holding the note may be different.

Servicing transfers are common and are governed by RESPA's borrower-protection requirements: the prior servicer must notify the borrower 15 days before transfer, the new servicer must notify within 15 days after, payments sent to the old servicer in the first 60 days after transfer cannot be charged as late, and so on. Borrowers experiencing a servicing transfer should preserve documentation through the transition.

Escrow accounts

Most mortgage borrowers pay into an escrow account each month, held by the servicer, that pays property taxes, homeowners insurance, and (where applicable) mortgage insurance when those bills come due. The escrow portion of the monthly payment is in addition to the principal and interest; the servicer estimates annual escrow needs, divides by 12, and adds the result to each monthly payment.

Escrow accounts are governed by RESPA and Regulation X. The servicer must analyze the escrow account at least annually, compare the projected balance to actual disbursements, and refund any surplus above a defined cushion to the borrower or apply it to the escrow account. Shortages (typically caused by property-tax increases) must be made up over the following twelve months either through a one-time payment or through increased monthly escrow contributions. Borrowers who experience surprise increases in their monthly payment should request the escrow analysis the servicer is required to provide.

For conventional loans above 80% LTV at origination, private mortgage insurance (PMI) is typically required and is paid through escrow. Under the Homeowners Protection Act of 1998, the borrower has the right to request PMI cancellation when LTV reaches 80% (based on the original property value) and PMI must be automatically terminated when LTV reaches 78%.

Points

Discount points are upfront payments to the lender that reduce the loan's interest rate over its term. One point equals 1% of the loan principal; in exchange, the lender typically reduces the rate by 0.125% to 0.25% per point, with the specific buy-down ratio varying by lender and product. Points are part of the finance charge for APR purposes and appear on the TILA disclosure.

Whether buying points produces net savings depends on how long the borrower keeps the loan: at closing, the borrower pays the point cost; over the term, the borrower saves interest at the lower rate. The breakeven horizon — the number of months at which accumulated interest savings equals the upfront point cost — is typically several years. A borrower who refinances or sells before the breakeven horizon pays more in points than they save in rate; a borrower who keeps the loan past the breakeven horizon comes out ahead.

The TRID disclosure regime

Since October 2015, U.S. residential mortgage transactions have been disclosed under the integrated TILA/RESPA disclosures, known as TRID. The borrower receives a Loan Estimate within three business days of submitting an application, showing the loan terms, projected payments, costs at closing, and other key disclosures. The borrower receives a Closing Disclosure at least three business days before consummation, showing the final terms and costs. The three-day waiting period gives the borrower time to compare the Closing Disclosure to the earlier Loan Estimate; material changes can require a revised disclosure and an additional waiting period.

The Loan Estimate and Closing Disclosure replaced the previous Good Faith Estimate, HUD-1, and Truth in Lending statement, integrating the TILA and RESPA disclosure regimes that had previously operated in parallel. The CFPB's TRID rule has been amended several times since 2015 to clarify specific issues; the basic framework is durable.

Limits and uncertainty

The basic structure of U.S. residential mortgages — the dominant 30-year fixed-rate product, the secondary-market role of Fannie and Freddie, the servicing structure, the TRID disclosure regime — has been stable since the post-2008 regulatory rewrite. Live developments include the FHFA's ongoing review of credit-score model use in mortgage underwriting (the VantageScore 4.0 transition), continued debate about the long-term status of Fannie Mae and Freddie Mac (in conservatorship since 2008), and periodic adjustment to the conforming loan limit. The framework as described is durable; specific dollar limits and product variants continue to evolve.