Finance category

Mortgage, loan, investing, tax, and money calculators.

Prepaid Interest Calculator

At closing, lenders collect per-diem interest from the closing date through the end of the month. This calculator shows exactly how much based on your loan, rate, and closing date.

Loan amount

Interest rate

Closing day of month

Days in closing month

Total prepaid interest

$943

collected at closing

Daily interest

$72.52

Days charged

closing day through end of month

How prepaid interest works

Mortgage interest is paid in arrears. Your first regular payment usually arrives in the second month after closing. To bridge the gap, the lender collects per-diem interest at closing covering the period from the closing date through the end of the closing month.

Closing later in the month means less prepaid interest at closing — but the same total interest paid over the loan. Some buyers time closings near month-end to reduce cash needed at closing, knowing the first regular payment hits sooner.

Editorial noteMaintained by EveryCalc - Reviewed June 2026

EveryCalc calculators are designed for fast, practical estimates with transparent inputs and no required account. We use plain formulas, visible assumptions, and related tools so visitors can check the result from more than one angle.

Results are informational only. For financial, tax, legal, medical, construction, or other high-impact decisions, verify the output against primary sources or a qualified professional.

Learn more about our review process on the EveryCalc methodology page.

How this calculator works

What this page estimates

This Prepaid Interest Calculator is built to give a quick, browser-based estimate for prepaid interest. At closing, lenders collect per-diem interest from the closing date through the end of the month. This calculator shows exactly how much based on your loan, rate, and closing date. The inputs stay on the page during normal use, and the result should be treated as an estimate for planning, comparison, or education rather than professional advice.

Calculation approach

The calculator applies the standard relationship implied by the inputs, then formats the answer so it can be checked and reused. For finance tools, the most important step is using consistent units, rates, time periods, and assumptions before comparing the result with another calculator or outside quote.

Example workflow

For example, start with a realistic value you already know, change one input at a time, and watch how the answer moves. That makes it easier to tell whether the result is being driven by the main amount, the rate, the time period, or a unit conversion.

Practical checks

Use current, real-world numbers when the result affects money, health, tax, or legal decisions.
Run a low, base, and high case when the inputs are estimates.
Check the related calculators below when the next decision depends on a different assumption.

How to interpret the prepaid interest result

Best use

Use the result as a planning number for comparing payments, rates, returns, tax reserves, or cash-flow choices before you request a quote or make a commitment.

Cross-check

Compare the answer with the contract, lender estimate, tax form, brokerage statement, payroll record, or invoice that will control the real-world outcome.

Watch for

Do not rely on a single optimistic rate, return, or fee assumption. Money pages work best when you run low, base, and high cases and keep professional advice separate from the estimate.

This page belongs to the Finance calculator library, so the answer should be read in the context of the decision you are modeling rather than as a universal rule.

Before relying on this prepaid interest estimate

Most calculator mistakes come from the inputs, not the arithmetic. Use this short audit before you reuse the answer in a spreadsheet, quote, application, or important conversation.

Confirm source numbers

Match balances, rates, fees, taxes, income, and payment dates against the lender quote, payroll record, tax form, statement, invoice, or contract.

Separate cash flow from total cost

A lower monthly payment can still cost more over time if fees, interest, taxes, or a longer term are hidden in the structure.

Run conservative cases

Test at least one higher-cost or lower-return case before using the output for a purchase, refinance, investment, loan, or tax decision.

Rerun this page when the rate, price, term, fee, tax rule, income, expense, or expected holding period changes.

How to Use

Enter the loan amount and locked rate.
Enter the day of the month you'll close.
Enter the days in your closing month (28–31).
Read the prepaid interest amount — this lands in the prepaid section of your closing disclosure.

Frequently Asked Questions

Why do lenders collect prepaid interest?

Mortgage interest is paid in arrears. Your first regular monthly payment covers the prior month. To handle the partial month from closing to the start of the regular cycle, lenders collect per-diem interest at closing.

Does closing later in the month save money?

It reduces cash to close because fewer days of prepaid interest are collected. But the first full payment hits sooner. Total interest paid over the life of the loan is identical either way.

Is prepaid interest tax-deductible?

If you itemize, prepaid mortgage interest is generally deductible in the year paid (subject to current tax rules). It's reported on the year-end 1098 along with other interest.

What's a 365-day year vs 360-day year?

Most US residential lenders use 365 days for per-diem interest. Some commercial lenders use 360. The difference rounds to roughly 1.4% on the daily figure — not large, but worth confirming on your closing disclosure.