Mortgage recast vs. refinance: what a lump sum really does

By the CalcLedger editorial team · Updated October 2026 · 7 min read · Examples use illustrative rates · How we calculate

The short answer: a recast re-spreads your lower balance over the same remaining term at the same rate, so your payment drops but your payoff date does not. On a $300,000 balance at 6.5% with 25 years left, a $50,000 lump sum cuts principal and interest from $2,026 to $1,688 a month.

If you have a bonus, an inheritance or money from selling another home, putting it toward the mortgage is a guaranteed return equal to your rate. The question is what you want back: a lower monthly payment, an earlier payoff date, or both. A recast and a refinance answer that question very differently.

What a mortgage recast is

Fannie Mae describes a recast this way: the borrower "pays a substantial principal curtailment after the loan has closed, and the monthly loan payment amount is recalculated over the remaining loan term based on the new outstanding balance." Its servicing job aid adds that the servicer reduces "the P&I payment only", using "the current interest rate and remaining loan term".

So three things stay fixed: your interest rate, your payoff date and your escrow for taxes and insurance. Only the principal-and-interest part of the bill gets smaller. There is no new loan: the servicer re-amortizes the lower balance.

Whether you can recast is up to your servicer and the loan's program. Servicers set their own minimum lump sum and fee, and some loans are not eligible, so ask in writing before you send money. Also check your note for a prepayment penalty: the Consumer Financial Protection Bureau defines it as "a fee that some lenders charge if you pay off all or part of your mortgage early."

What a lump sum saves: recast vs. keep paying

Here is a $300,000 balance at 6.5% with 300 payments (25 years) left. Today's payment is $2,026. The table shows the new payment after a recast and the interest saved two ways, before any recast fee: recasting, or paying the same lump sum and keeping the $2,026 payment.

Keeping the old payment ends the loan 23, 53, 95 and 158 payments early for the four lump sums. The recast saves less because the loan still runs to the same end date: you pay less each month for the full 25 years instead of finishing early.

Why the big gap? After a recast, part of each month's savings is money you simply do not send to the lender, so less principal is paid each month and interest keeps running on a larger balance. If you keep sending the old amount, every extra dollar goes to principal, and the balance falls faster each month.

Recast vs. refinance

A refinance replaces your loan with a new one at a new rate, usually with thousands in closing costs and a new 30-year clock. With the Freddie Mac 30-year average at 7.28% on October 1, 2026, that only makes sense if your current rate is clearly higher. Both options below use the same $50,000 lump sum, a $250 recast fee and $6,000 of refinance closing costs; the last column is all remaining interest plus those costs.

With a 6.5% loan, the 30-year refinance looks similar on the monthly bill ($1,711 vs. $1,688) but costs $115,136 more, because you pay a higher rate for five more years. Even the 25-year refinance costs $42,900 more. With an 8% loan, the math flips: refinancing at 7.28% over the same 25 years gives a lower payment ($1,812 vs. $1,930) and costs $29,557 less, if you qualify.

Rates change every week, so run your own numbers in the mortgage recast calculator, which compares all three options side by side, and check the break-even of any refinance offer in the refinance calculator.

Recasting and PMI

A recast does not cancel private mortgage insurance by itself. But the lump sum lowers your balance, and the CFPB Bulletin 2015-03 says you can request PMI cancellation once your balance reaches 80% of the original value "based on actual payments". If your lump sum gets you there, send a written cancellation request to your servicer as well. The PMI removal date calculator shows when you reach 80%.

When each option makes sense

• Recast if you want a lower required payment, your rate is at or below today's rates, and your servicer offers it for a small fee.
• Lump sum without a recast if your only goal is to be debt-free sooner and you are comfortable with the current payment.
• Recast and keep paying the old amount if you want the early payoff but also a safety net.
• Refinance if you can get a rate clearly below yours and plan to stay long enough to earn back the closing costs.
• Neither if the money is your emergency fund or you carry higher-rate debt.

How to request a recast

1. Call or write your servicer and ask whether your loan can be recast, the minimum lump sum, the fee and how long processing takes.
2. Get it in writing, including how the lump sum will be applied: to principal, not to future payments.
3. Stay current on your regular payments while the recast is processed.
4. Check the new payment on your next statement against the recast calculator.

Frequently asked questions

What is a mortgage recast?
You pay a large lump sum toward principal and your servicer recalculates the monthly payment on the lower balance over the same remaining term at the same rate. On $300,000 at 6.5% with 25 years left, a $50,000 lump sum lowers principal and interest from $2,026 to $1,688.

Is it better to recast or pay extra principal?
Paying extra and keeping the same payment saves more interest: $143,646 vs. $51,281 on the $50,000 example, and the loan ends 95 payments sooner. A recast gives you a lower required payment instead. Recasting and then paying the old amount by choice gives you both.

Does a recast change my interest rate?
No. Fannie Mae's guidance re-amortizes the balance at the current interest rate and remaining term. To change the rate you need a refinance.

Should I recast or refinance with rates above 7%?
If your current rate is below about 7.28% (the Freddie Mac average on October 1, 2026), a recast usually wins: on a 6.5% loan, refinancing the same balance into a 30-year loan costs $115,136 more. A refinance can win if your rate is clearly higher, for example 8%.

Can every mortgage be recast?
No. It is up to your servicer and the loan program, and each servicer sets its own minimum and fee. Ask before sending a lump sum.

Example figures are illustrative, principal and interest only. Your servicer confirms whether a recast is available and your new payment.

Sources

• Fannie Mae: Re-amortized (recast) mortgages
• Fannie Mae: Processing a principal curtailment on a recast loan
• Consumer Financial Protection Bureau: Mortgage key terms
• Consumer Financial Protection Bureau: Bulletin 2015-03: PMI cancellation and termination
• Freddie Mac: Primary Mortgage Market Survey (weekly mortgage rates)

Rules, limits and program details are checked against these official sources. Example numbers are calculated by CalcLedger with the formulas on our how we calculate page. Read our editorial policy.