How a 3-2-1 buydown works, and how to size one

Temporary buydowns come back into fashion whenever rates rise and sellers need a concession that moves a listing. The structure is genuinely useful and genuinely misunderstood, mostly because the marketing describes the payment relief and skips the part where the rate goes back up.

This page explains the mechanics, the regulatory treatment, and the questions that decide whether a 3-2-1 is a good idea for a specific buyer. It deliberately carries no rate or payment figures. The numbers that matter are yours, and they belong on a Loan Estimate rather than in an article.

What is a 3-2-1 buydown?

A 3-2-1 buydown is a temporary interest-rate reduction on a fixed-rate mortgage. The name is the schedule: the rate is reduced by three percentage points below the note rate in year one, two points in year two, and one point in year three. From year four to the end of the term, the borrower pays the note rate.

The note rate itself never changes. This is not an adjustable-rate mortgage, and there is no index, margin or cap structure involved. The underlying loan is a fixed-rate loan the entire time. What changes is how much of the interest the borrower is responsible for paying in those first three years, because the rest has already been deposited.

The 2-1 and 1-0 buydowns are the same idea over shorter schedules. A 2-1 reduces the rate by two points then one; a 1-0 reduces it by one point for a single year. Our guide to temporary buydowns compares the three structures.

How does the money actually move?

This is the part that clears up most of the confusion. Nothing is subsidised in the ordinary sense and no cost is absorbed by the lender.

1. The total of all the reductions is computed up front. Add together every dollar of interest the borrower will not be paying across the three years.
2. That whole amount is deposited at closing into a buydown account held by the servicer.
3. Each month, the borrower pays the reduced amount and the servicer draws the difference from the account to make the lender whole.
4. The account empties on schedule at the end of year three, and the borrower's payment steps up to the note-rate payment.

So the lender receives the full contractual payment every single month from month one. The borrower simply is not the one paying all of it at first. Reg Z's commentary describes this directly: a seller or other third party pays an amount, to the creditor or to the consumer, to reduce the consumer's payments for all or a portion of the credit term.

How do you calculate a 3-2-1 buydown?

The arithmetic is simple; getting the right inputs is the hard part. To size a 3-2-1 you need four things:

• The note rate on the loan as it is actually locked, not an advertised or assumed rate.
• The loan amount after the down payment and any financed fees.
• The loan term, since the amortisation schedule determines the interest in each year.
• Whether the buydown is on the credit contract or a separate agreement, which changes the disclosures.

From there the method is:

1. Amortise the loan at the note rate and record the scheduled payment.
2. Amortise it again at the note rate minus three points, minus two points, and minus one point.
3. For each of the first three years, take the difference between the note-rate payment and the reduced payment, multiplied by twelve.
4. Add the three annual totals. That sum is the buydown cost, and it is what must be deposited at closing.

We deliberately do not publish a buydown payment calculator on this page. Payment and finance-charge figures are advertising trigger terms under Regulation Z, and a buydown reflected in the credit contract also requires a composite annual percentage rate rather than a simple one. Producing those numbers responsibly means producing them on a Loan Estimate for your actual file, which is the document designed for it and the only one you can compare between lenders.

Which rate do you have to qualify at?

Almost always the note rate, not the reduced year-one rate. This is the point that surprises buyers most, and it is the one that determines whether a buydown helps them at all.

The logic is straightforward from the underwriter's side. The temporary reduction expires, and the borrower will be responsible for the full payment for the overwhelming majority of the loan's life. Qualifying someone on a payment that lasts twelve months would be underwriting a payment they are not, in the long run, obliged to afford.

The practical consequence: a 3-2-1 buydown does not increase how much house a buyer can qualify for. It changes the early cash flow of a loan they already qualified for. If a buyer needs the buydown to pass debt-to-income, the buydown is not the right tool and the file needs a different structure. Our guide on how debt-to-income is calculated covers the ratio that governs this.

How is a buydown treated on the disclosures?

This is where buydowns get genuinely technical, and where the answer depends on paperwork most buyers never see. Regulation Z's Official Interpretations to section 1026.17(c) draw a sharp line.

If the buydown is reflected in the credit contract

The finance charge and every disclosure affected by it must account for the buydown as an amendment to the contract's interest-rate provision. The annual percentage rate must be a composite rate reflecting both the lower initial rate and the higher subsequent rate, and the payment disclosures must show the two payment levels.

If the buydown is not reflected in the credit contract

Where the buydown sits in a separate agreement and the consumer is legally bound to the full note rate from the outset, the lender's finance charge and related disclosures must not reflect the buydown at all. The annual percentage rate and payment disclosures ignore the temporary reduction entirely.

Either way, the seller's contribution shows up

The amount the seller pays is treated as seller's points and is not part of the finance charge, but it is disclosed as a credit from the seller in the transaction summaries on the closing disclosure.

Reg Z also addresses consumer buydowns, where the borrower rather than a third party pays the amount. Those must be reflected as an amendment to the contract's interest-rate provision in the finance-charge disclosure.

Why this matters to a buyer: two buydowns that feel identical in a sales conversation can produce different annual percentage rates on the paperwork depending purely on how the agreement was documented. When comparing offers, compare Loan Estimates, and ask specifically whether the buydown is on the note.

3-2-1 buydown or discount points?

They solve different problems and are constantly conflated.

A seller concession can often be directed to either. That is a real decision worth making deliberately: the same concession spent on points buys a smaller reduction that never expires, and spent on a 3-2-1 buys a larger reduction that does. Our guide to buying discount points works through the break-even side.

What happens if you sell or refinance early?

The buydown account is prepaid, so money may still be sitting in it when the loan is paid off. Where that happens, the unused balance is typically applied to the payoff of the loan rather than refunded as cash, though the governing terms are in the buydown agreement itself and should be read.

This is a real advantage over discount points, where an early exit means the cost is largely sunk. It also means a buyer expecting to refinance is not necessarily wasting a 3-2-1 the way they might waste points. Ask for the buydown agreement and confirm how unused funds are handled before assuming either outcome.

When is a 3-2-1 buydown actually a good idea?

Honestly assessed, it is a good tool in a narrow set of circumstances and an expensive distraction outside them.

It tends to work when:

• A seller or builder is offering a concession that would otherwise go to a price reduction the buyer values less.
• The buyer's income is genuinely expected to rise within three years for a reason that already exists.
• The buyer has near-term costs concentrated in the first year or two, such as furnishing or renovation.
• The buyer comfortably qualifies at the note rate and simply prefers the early cash flow.

It tends not to work when:

• The buyer needs the reduced payment to afford the home at all. Year four is not optional.
• The buyer is counting on refinancing before the step-up. That is a bet on future rates, not a plan.
• The same concession would do more as a price reduction or as permanent points, which is worth actually comparing rather than assuming.

The comparison that settles it is not the year-one payment. It is the total of what the concession buys under each option against how long the buyer realistically keeps the loan.

Frequently asked questions

The bottom line

A 3-2-1 buydown reduces the rate by three, two, and one percentage point across the first three years of a fixed-rate loan, then ends. The full cost is deposited at closing, usually by a seller or builder, and released monthly to the servicer. You generally still qualify at the note rate, so it does not buy more house. And how it appears on your disclosures, including whether the annual percentage rate is a composite, depends on whether the buydown sits on the credit contract or beside it.

If someone has offered you a buydown, the useful next step is seeing the actual schedule against your actual loan on a Loan Estimate, alongside what the same concession would buy as points or as a price reduction. Valley West Mortgage is a Las Vegas lender, NMLS #65506, and you can start with a fast quote.

Last updated: August 4, 2026 — rebuilt. The disclosure treatment on this page was verified verbatim against Regulation Z's Official Interpretations, Supplement I to 12 CFR Part 1026, commentary to section 1026.17(c) paragraphs 3 and 4, on the eCFR on August 4, 2026, including the composite annual percentage rate requirement and the seller-credit treatment. This page carries no rate, payment or cost figures by design.