# How a mortgage rate lock works

> What a rate lock covers, how long to lock, what can still change your rate, how locks tie into Loan Estimate timing, and what a rate move costs.

URL: https://mail.mortgage-math-us.com/blog/how-a-rate-lock-works/  
Last reviewed: 2026-10-29 · By the MortgageMath US Editorial team

## Quick answer

A rate lock holds your interest rate, and the points or credits tied to it, until a set date — typically 30, 45 or 60 days — as long as your loan and application don’t change. If you lock after your Loan Estimate, the lender must send a revised one within 3 business days. Without a lock, a move of just a quarter point before closing would add about **$58 a month** to a $340,000 30-year loan at today’s 7.24% average.

## Key facts

| Fact | Value | Source | As of |
|---|---|---|---|
| Typical rate lock periods | 30, 45 or 60 days | [CFPB](https://www.consumerfinance.gov/ask-cfpb/whats-a-lock-in-or-a-rate-lock-en-143/) | Oct 28, 2026 |
| Revised Loan Estimate after you lock | 3 business days | [12 CFR 1026.19(e)(3)(iv)(D)](https://www.ecfr.gov/current/title-12/chapter-X/part-1026/subpart-C/section-1026.19) | Oct 29, 2026 |
| Last revised Loan Estimate before closing | 4 business days | [12 CFR 1026.19(e)(4)(ii)](https://www.ecfr.gov/current/title-12/chapter-X/part-1026/subpart-C/section-1026.19) | Oct 29, 2026 |
| Closing Disclosure before closing | 3 business days | [CFPB](https://www.consumerfinance.gov/owning-a-home/closing-disclosure/) | Oct 28, 2026 |
| 30-year fixed average used here | 7.24% | [Freddie Mac Primary Mortgage Market Survey](https://www.freddiemac.com/pmms) | Week of Oct 29, 2026 |

## What a lock covers — and what it doesn’t

A [rate lock](https://mail.mortgage-math-us.com/glossary/rate-lock/) is the lender’s promise to honor a specific price for your loan: an interest rate plus any discount points or lender credit that go with it. The CFPB describes it as a rate that won’t change between the offer and closing, provided you close within the lock period and your application stays the same.

That last condition does a lot of work. The lock is priced for a particular loan — amount, down payment, loan type, credit score, property and occupancy. Change any of those and the lender can reprice the loan, lock or no lock. And a lock is only as good as its date: if closing slips past it, you need an extension or a new lock at whatever the market offers that day.

Some lenders lock when they issue the Loan Estimate, some don’t. The top of page 1 says whether the rate is locked and until when; if it isn’t, the CFPB notes, the rate can change at any time. For what drives the rate in the first place, see [how mortgage rates work](https://mail.mortgage-math-us.com/buying/mortgage-rates/).

## Choosing a lock length

The CFPB says locks are typically available for 30, 45 or 60 days, sometimes longer, and that extending one can be expensive. Longer locks protect you for more time but may be priced higher, so ask each lender what its shorter and longer locks cost — the Loan Estimate doesn’t show it.

The lock has to outlast the disclosure clock as well as underwriting, the appraisal and the title work. These are the federal timing rules that sit inside every lock:

*Federal timing rules a lock has to fit around*

| Step | Rule | What it means for the lock |
|---|---|---|
| Loan Estimate after application | Within 3 business days | A lock offered with it shows on page 1 |
| You say you want to proceed | Within 10 business days, or the lender may revise the estimate | Locking early doesn’t stop the clock on this |
| Lock after the first estimate | Revised Loan Estimate within 3 business days | Shows the locked rate, points and credits |
| Changed circumstance | Revised estimate within 3 business days of the lender learning of it | A repriced lock arrives this way |
| Last revised Loan Estimate | Must reach you at least 4 business days before closing | Late repricing can push the closing date |
| Earliest closing after the first estimate | At least 7 business days after it is delivered or mailed | Sets the shortest possible lock you could use |
| Closing Disclosure | At least 3 business days before closing | A new wait starts if the APR rises by more than 0.125% |

The disclosure deadlines count business days, while a lock’s length is usually counted in calendar days, so a 30-day lock covers only about four working weeks. If your purchase contract allows a longer closing, size the lock to the contract date plus a cushion.

## How the lock shows up on your Loan Estimate

Before you lock, the points and lender credits on your [Loan Estimate](https://mail.mortgage-math-us.com/buying/loan-estimate/) can still change, because the rules let the lender revise them when the rate is locked. Once you lock, discount points fall under the zero-tolerance category: they can’t go up at closing unless something on the list of valid changed circumstances happens, such as a change you asked for or new information about your credit, income or the property.

If the lender does reprice the lock for a valid reason, it must document it with a revised Loan Estimate within 3 business days. It can’t send a revised Loan Estimate after the Closing Disclosure has been issued; changes after that point appear on a corrected Closing Disclosure instead.

## What can change a locked rate

*Common reasons a locked loan is repriced*

| What changes | Why it matters | How to avoid it |
|---|---|---|
| Loan amount or down payment | The price depends on loan size and loan-to-value | Settle your down payment before you lock |
| Loan type or term | A different product is a different price | Choose the product first, then lock |
| Appraisal higher or lower than expected | The loan-to-value ratio moves | Leave room in your budget for a low appraisal |
| Credit score | A new loan or a missed payment can drop your score | Don’t open credit or miss payments before closing |
| Income the lender can’t document | Your debt-to-income ratio changes | Hand over pay records and explanations early |
| Job change | Lenders re-verify employment close to closing — Fannie Mae within 10 business days of the note date | Tell your lender before you change jobs |
| Closing delayed past the lock date | The lock expires | Lock long enough, and ask about extensions in advance |

Lenders also need documents to be current: Fannie Mae requires credit, income, employment and asset documents to be no more than 4 months old on the note date, so a long delay can mean new paperwork as well as a new lock.

## What a rate move costs while you wait

In the latest week alone Freddie Mac’s average fell from 7.32% to 7.24% — 0.08 percentage point, worth about $18 a month on this loan. Here is what moves of different sizes would do to a $340,000 30-year fixed loan, starting from today’s 7.24% average:

> **Worked example: A $340,000 30-year fixed loan if the rate rises before you lock**
>
> | Rate rise (percentage points) | New rate | Principal and interest | Extra a month | Extra a year | Extra over 5 years | DTI change on $9,000 a month |
> |---|---:|---:|---:|---:|---:|---:|
> | +0.125 | 7.37% | $2,346 | +$29 | +$347 | +$1,733 | +0.3 pts |
> | +0.25 | 7.49% | $2,375 | +$58 | +$695 | +$3,474 | +0.6 pts |
> | +0.5 | 7.74% | $2,433 | +$116 | +$1,396 | +$6,982 | +1.3 pts |
> | +0.75 | 7.99% | $2,492 | +$175 | +$2,104 | +$10,520 | +1.9 pts |
> | +1 | 8.24% | $2,552 | +$235 | +$2,818 | +$14,089 | +2.6 pts |
> 
> At today’s rate the payment is $2,317, which is 25.7% of $9,000 in gross monthly income. Every quarter point adds about $58 a month.

Two things follow. First, even small moves add up over a loan’s life, and a lock removes that risk for the weeks before closing. Second, a bigger rise can do more than raise the payment — it can push your [debt-to-income ratio](https://mail.mortgage-math-us.com/buying/debt-to-income/) over a lender’s limit. If you are near the edge, lock as soon as you have a contract. The [affordability calculator](https://mail.mortgage-math-us.com/tools/affordability-calculator/) shows how much room you have.

> **Tip: Lock the loan you’ll actually close**
>
> Settle the loan type, down payment and points before you lock. Changing any of them later lets the lender reprice, which can undo the protection you paid for with the lock.

## Extensions, relocks and float-downs

No federal rule sets what a lender charges for these, so terms vary by lender. Get them in writing when you lock.

- **Extensions.** If closing slips, many lenders will extend the lock for a fee or a slightly higher rate. The CFPB warns that extensions can be expensive; ask the price per extra day or week before you choose a lock length.
- **Expired locks.** If a lock lapses, the lender may relock you at the current market rate — and some use the worse of the original and current rate. Ask which policy applies.
- **Float-downs.** Some lenders sell a one-time option to take a lower rate if the market falls by a set amount before closing. It costs money up front, so it is a bet on rates falling; compare its price with the monthly figures above.
- **Paying for a lower rate.** Buying points at lock time is a separate choice; see [points or a bigger down payment](https://mail.mortgage-math-us.com/blog/points-or-bigger-down-payment/) for when it pays.

## When to lock: a checklist

**How to lock your mortgage rate**

1. **Shop before you lock** — Compare Loan Estimates from several lenders on the same day; credit checks within 45 days count as one inquiry.
2. **Sign the purchase contract** — Most borrowers lock once they have a property and a closing date.
3. **Pick a lock that covers the contract date plus a cushion** — Ask what longer locks and extensions cost.
4. **Get the lock in writing** — Rate, points or credits, the expiration date and the extension policy.
5. **Check the revised Loan Estimate** — It should arrive within 3 business days if you locked after the first one.
6. **Keep your file stable until closing** — No new credit, job changes or large unexplained deposits without telling your lender.
7. **Review the Closing Disclosure** — It arrives at least 3 business days before closing; confirm the rate matches your lock.

[Open the mortgage payment calculator](https://mail.mortgage-math-us.com/tools/mortgage-payment-calculator/)

## Frequently asked questions

### How long does a mortgage rate lock last?

Typically 30, 45 or 60 days, according to the CFPB, and sometimes longer. Longer locks can cost more, and extensions can be expensive, so choose a lock that covers your contract’s closing date with some room.

### Does locking my rate cost money?

It can. Longer locks may be priced higher, extensions can be expensive and some lenders charge a separate lock fee. The Loan Estimate doesn’t show what other lock periods cost, so the CFPB suggests asking.

### Can my rate change after I lock?

Yes, if your application changes — a different loan amount or down payment, a new credit score, an appraisal above or below the estimate, or income the lender can’t document — or if the lock expires before closing.

### What happens if my rate lock expires?

You can extend it, usually for a fee or a higher rate, or relock at the current market rate. Some lenders relock at the worse of the old and new rates. Ask about the policy when you lock.

### Do I get a new Loan Estimate when I lock?

If the rate wasn’t locked when you got your first Loan Estimate, the lender must send a revised one within 3 business days of the lock, showing the locked rate, points and credits. It must reach you at least 4 business days before closing.

### How much does a rate increase cost if I don’t lock?

On a $340,000 30-year loan at today’s 7.24% average, a quarter-point rise adds about $58 a month and a half-point rise about $116 — $1,396 a year.

### What is a float-down option?

An option some lenders sell that lets you take a lower rate once if the market falls by a set amount before closing. Terms and costs vary by lender; no federal rule requires or prices it.

## Sources

- [Freddie Mac Primary Mortgage Market Survey](https://www.freddiemac.com/pmms) — 30-year fixed rate, national weekly average; 30-year fixed rate, previous week (Week of Oct 29, 2026)
- [CFPB](https://www.consumerfinance.gov/ask-cfpb/whats-a-lock-in-or-a-rate-lock-en-143/) — Typical rate lock periods (Oct 28, 2026)
- [12 CFR 1026.19(e)(3)(iv)(D)](https://www.ecfr.gov/current/title-12/chapter-X/part-1026/subpart-C/section-1026.19) — Revised Loan Estimate due within this many business days after you lock a rate that was floating; Lender may revise the Loan Estimate if you indicate intent to proceed after more than this many business days; Revised Loan Estimate due within this many business days of learning of a changed circumstance (Oct 29, 2026)
- [CFPB](https://www.consumerfinance.gov/ask-cfpb/what-is-a-loan-estimate-en-1995/) — Lender must send the Loan Estimate within this many business days of your application (Oct 28, 2026)
- [CFPB](https://www.consumerfinance.gov/owning-a-home/closing-disclosure/) — You receive the Closing Disclosure at least this many business days before closing (Oct 28, 2026)
- [12 CFR 1026.22](https://www.ecfr.gov/current/title-12/chapter-X/part-1026/subpart-C/section-1026.22) — APR change that triggers a new 3-business-day wait (regular loans) (Oct 28, 2026)
- [Fannie Mae Selling Guide B3-3.1-04](https://selling-guide.fanniemae.com/sel/b3-3.1-04/verbal-verification-employment) — Fannie Mae: employment re-verified no more than this many business days before the note date (Oct 7, 2026)
- [Fannie Mae Selling Guide B1-1-03](https://selling-guide.fanniemae.com/sel/b1-1-03/allowable-age-credit-documents-and-federal-income-tax-returns) — Fannie Mae: credit, income, employment and asset documents may be no older than this on the note date (Apr 2, 2025)
- [CFPB](https://www.consumerfinance.gov/ask-cfpb/what-exactly-happens-when-a-mortgage-lender-checks-my-credit-en-2005/) — Mortgage credit checks within this window count as one inquiry (Aug 28, 2026)
- [CFPB: What’s a lock-in or a rate lock?](https://www.consumerfinance.gov/ask-cfpb/whats-a-lock-in-or-a-rate-lock-en-143/)
- [eCFR: 12 CFR 1026.19, Loan Estimate timing and revisions](https://www.ecfr.gov/current/title-12/chapter-X/part-1026/subpart-C/section-1026.19)
- [CFPB: Loan Estimate explainer](https://www.consumerfinance.gov/owning-a-home/loan-estimate/)

_General information, not financial advice._