Mortgage Recast After Lump Sum Calculator

How to use this mortgage recast after lump sum calculator

1. Current mortgage balance: enter the amount in your selected currency. The worked example uses $240,000.00.
2. Lump sum toward principal: enter the amount in your selected currency. The worked example uses $40,000.00.
3. Annual interest rate: enter a percentage using 5 to mean 5%. The worked example uses 6%.
4. Remaining months: enter the quantity in months. The worked example uses 300 months.
5. Recast fee paid in cash: enter the amount in your selected currency. The worked example uses $300.00.

Start with figures from the same statement date or planning period. Calculate once, save scenario A, then change one assumption to understand its effect. The comparison shows B minus A; a positive difference means the result increased, which is not automatically better.

Formula and calculation method

New payment = PMT(balance − lump sum, annual rate / 12, remaining months).

The calculator evaluates this relationship directly in your browser. The displayed precision is for readability and does not imply a guaranteed outcome. Time periods and rate conventions matter: use the exact units in each input label and avoid mixing monthly and annual values.

What the result means

A recast lowers the payment while keeping the rate and remaining term. It differs from simply making a lump-sum payment and continuing the original payment, which can shorten repayment.

Two worked examples

1. Illustrative planning scenario

Current mortgage balance = $240,000.00; Lump sum toward principal = $40,000.00; Annual interest rate = 6%; Remaining months = 300 months; Recast fee paid in cash = $300.00.

Apply the stated formula with these inputs. Monetary examples use USD; percentages are divided by 100 inside the calculation. Intermediate calculations retain full precision and displayed amounts are rounded.

2. Simplified calculation check

Current mortgage balance = $12,000.00; Lump sum toward principal = $2,000.00; Annual interest rate = 0%; Remaining months = 10 months; Recast fee paid in cash = $100.00.

Apply the stated formula with these inputs. Monetary examples use USD; percentages are divided by 100 inside the calculation. Intermediate calculations retain full precision and displayed amounts are rounded.

The second example uses simpler inputs to make the arithmetic easier to check. It is also included in the automated regression suite. These examples illustrate the model and are not market averages, live offers or personalized advice.

Assumptions and limitations

Assumes the lender permits a recast and keeps the rate and term unchanged. Fee is paid separately and is not financed.

Use this output to frame a question or compare consistent scenarios. Reconcile any decision involving an actual product, employment agreement or financial statement with its underlying documents. If a contract uses different rounding or timing, its result may differ from this estimate.

Frequently asked questions

Sources and verification

The following primary sources provide background on the financial concepts. CalcPane’s formula and assumptions above define this specific model; these organizations do not endorse CalcPane or certify its outputs.

• CFPB — How mortgage payments are calculated
• CFPB — Your Money, Your Goals toolkit

Formula implementation and worked examples checked by automated tests on 2026-10-17. Inspect this calculator’s inputs and expected outputs. Read our calculation methodology. Independent professional review has not been completed for this release.

Cite this calculator

CalcPane. (2026-10-17). Mortgage Recast After Lump Sum Calculator. https://calcpane.com/mortgage-recast-payment-calculator/

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