Practical decision guide
Recast or refinance after a lump-sum mortgage payment?
Recasting and refinancing solve different problems. A recast can reduce required principal-and-interest payments after a principal reduction while preserving the existing rate and remaining term. A refinance replaces the loan with new terms and costs.
Compare both with keeping the loan and with making the same principal payment while maintaining the existing monthly payment. The result depends on how long you keep the loan, how much cash remains available and how much debt remains at that time.
How to use this tool
Start with your latest statement
Enter the current balance, note interest rate and remaining months. Check that the estimated P&I matches your loan; taxes and insurance are separate.
Use one lump-sum amount
Apply the same principal amount to recast, refinance and extra-principal paths. Keep enough separate cash for transaction fees and reserves.
Get two actual quotes
Ask your servicer whether a recast is offered and obtain its fee. Enter a refinance quote with its new rate, term and net loan costs.
Choose your holding period
Compare interest plus fees, retained cash and remaining debt at the same month. Review the payoff timeline before favoring a lower payment.
Example 1: lower payment or earlier payoff
With $300,000 remaining at 6% over 240 months, estimated P&I is $2,149.29. Applying $50,000 and recasting the remaining $250,000 gives a payment of $1,791.08, about $358.22 less per month. A $250 recast fee is a separate cash cost.
Apply the same $50,000 and keep paying $2,149.29 instead, and the modeled loan pays off in 175 months, 65 months earlier. Over 60 months, recast interest plus its $250 fee is about $69,964; the extra-principal path incurs about $66,214 of interest. The latter requires larger monthly payments. These are illustrative assumptions, not quoted rates.
Example 2: a lower payment can cost more
With $100,000 remaining at 6% for 120 months, P&I is $1,110.21. Refinancing the same balance at the same 6% for 360 months, with no fees in this example, lowers P&I to $599.55.
After 60 months, the original schedule has about $57,426 in remaining debt and $24,038 in interest. The longer refinance has about $93,054 in debt and $29,027 in interest. Its smaller payment comes from slower repayment; it does not create an interest saving.
Check whether a recast is available
- Ask your servicer which loan types qualify, whether the loan must be current, and whether a minimum principal reduction or waiting period applies.
- Confirm the fee, required paperwork and date a new payment would begin. A principal payment alone does not guarantee a recast.
- Use the contractual principal-and-interest amount to validate the model if you have made earlier extra payments or your loan has unusual terms.
Read the refinance estimate beyond the payment
- Compare the new interest rate and repayment term separately. A longer term can lower the payment while increasing interest and debt at your chosen horizon.
- Separate actual loan costs from escrow deposits and prepaid items, and identify any lender credit or financed fees.
- Treat property value as common to all four paths. Principal repayments reduce debt rather than becoming a borrowing expense.
Sources and further reading
- Fannie Mae: principal curtailments and re-amortization — Servicer guidance on principal payments and recalculating P&I with the current rate and remaining term.
- Chase: mortgage recast process — An example of a servicer recast program, eligibility and payment treatment.
- CFPB: comparing Loan Estimates — Compare loan costs, payments and terms using actual lender disclosures.
Frequently asked questions
Does a mortgage recast change my interest rate?
The modeled recast keeps the existing note rate and remaining term and recalculates P&I on the balance after the principal payment. Whether your loan is eligible depends on your servicer and loan program.
What is the difference between recasting and paying extra principal?
Both reduce the balance. Recasting lowers the required P&I after approval; paying extra without recasting generally keeps the contractual payment and shortens payoff. This calculator compares those two paths using the same upfront principal reduction.
Can I finance the refinance closing costs?
The calculator lets you add the entered costs to the new loan if that is an available lender option. This reduces cash needed today but increases debt and interest. The fee itself is counted once, with interest on the financed amount counted as it accrues.
Is the lowest monthly payment the best result?
It may help cash flow, but it does not establish the lowest cost. Compare interest plus fees over your holding period, debt remaining at that point, cash retained and the full payoff timeline. This model holds spare cash at 0% and does not estimate investment alternatives or tax benefits.
What if my lump sum pays off the whole mortgage?
Principal paydown is capped at the remaining balance. The three paydown paths then pay off today, with no new recast or refinance transaction assumed. Any cash above the balance remains available. Obtain a lender payoff quote for actual accrued interest and other payoff charges.