Prepaid interest and per-diem charges: the daily interest between closing and your first payment
Of every line on a closing statement, prepaid interest is the one borrowers most often mistake for a fee. It is not a fee and nobody profits from it as profit. It is interest, charged by the day, for the stretch between the day your new loan funds and the day your normal monthly payment cycle takes over. Mortgage interest is paid in arrears, so your first regular payment covers the month just ended, and the partial month at the front of the loan has to be settled at closing. Understand the daily rate and the day count, and you can predict this line to the dollar before your Closing Disclosure arrives.
What prepaid interest is
CFPB defines prepaid interest charges as charges due at closing for any daily interest that accrues on your loan between the date you close on your mortgage loan and the period covered by your first monthly mortgage payment. It appears on page 2, Section F of both the Loan Estimate and the Closing Disclosure, among the prepaids, next to items like the first insurance premium and initial escrow deposits.
The structure follows from how mortgage payments work. A payment made on the first of a month pays the interest for the month that just passed. When a loan funds mid-month, the days from funding to month-end belong to no monthly payment yet, so they are collected at closing instead. The later in the month you close, the fewer odd days you prepay, and the sooner your first full payment comes due. The interest itself is owed either way; closing earlier or later only moves when you hand it over.
The per-diem arithmetic
Daily interest, the per diem, is the annual interest for one day. On the common 365-day basis, it is the loan amount multiplied by the note rate, divided by 365. A $400,000 loan at 6.50 percent accrues $26,000 of interest over a full year, so the per diem is about $71.23 a day. Fund ten days before month-end and the prepaid interest line is about $712. Your note and your lender's worksheet state the day-count basis they use, so ask for it and check their arithmetic with your own division.
That arithmetic is also your early-warning system. CFPB notes the prepaid interest figure may change between the Loan Estimate and the Closing Disclosure, because the day count cannot be final until the closing date is. If the final line surprises you, the cause is almost always a changed closing or funding date, not a changed rate. Count the days between funding and the first of the next month and multiply by the per diem. If the product does not match, ask which day they counted as day one.
Odd days, funding dates, and the closing calendar
Lenders call the partial-month days odd days, and the calendar controls how many you buy. Close on the 28th and you prepay two or three days. Close on the 3rd and you prepay nearly a full month of interest at the table, though your first regular payment then sits almost two months away. Neither is cheaper in total interest over the loan's life. The difference is cash timing: cash at closing now versus a payment holiday that is not really a holiday, just interest already settled.
Watch the distinction between signing and funding. Interest starts when the loan funds, which on a refinance follows the rescission period for most borrowers, so the funding date can land days after you sign. Your Closing Disclosure's prepaid interest is counted from funding, and a funding delay across a weekend adds per diems. When a closing slips by a week, this line, not the rate, is usually where the extra cash went.
Why the old loan's payoff date matters just as much
Two loans, two clocks. Interest on your old loan keeps accruing daily until the payoff funds reach the old servicer, and the payoff statement quotes a per diem and a good-through date for exactly that reason. Interest on the new loan starts at funding. A slow payoff, a weekend gap, or a payoff statement that expires adds days of old-loan interest; an overlapped day means you briefly paid interest on both loans for the same day.
Neither overlap nor gap is a lender trick; they are sequencing. The settlement agent wires the payoff from closing funds, and the dates on the Closing Disclosure and the payoff statement together determine the total daily interest you buy during the switch. Before closing, confirm the payoff good-through date covers the actual funding date with margin, and ask how many days of prepaid interest the disclosure assumes. Those two answers pin down the cash swing most borrowers find mysterious.
Where prepaid interest belongs in break-even math
Here is the coaching point the prepaids and escrow guide makes about all prepaids, applied to this one: prepaid interest is a timing item, not a true cost of choosing this loan. During those odd days you would have owed daily interest on the old loan anyway, at the old rate. Only the rate difference across a handful of days is genuinely incremental, a few dollars, while the full prepaid amount is cash you must bring to closing regardless.
So budget it, but do not break-even it. Cash to close includes prepaid interest, so it affects what you need in the bank and whether rolling costs into the balance makes sense. The break-even month, though, should be computed from true closing costs only: lender and third-party charges that buy the loan itself. Keep the per diem in the cash column, out of the cost column, and both numbers will tell you the truth.
Worked example
Stated example: a $400,000 balance, 27 years left on the current loan, a new 30-year term, $6,000 of true closing costs, and a planned stay of seven years. Suppose the new note rate is 6.50 percent: the per diem on a 365-day basis is about $71.23, so funding ten days before month-end puts about $712 of prepaid interest in Section F of the closing statement. That $712 is cash to close, on top of the $6,000, but it is not added to the $6,000 for the break-even test in the calculator, because daily interest for those ten days was owed on the old loan too.
The trap most people miss
The trap is adding prepaid interest into closing costs when you judge the refinance. It inflates the break-even by days of interest you would have paid anyway, and it can make a sound refinance look months worse than it is. Budget it as cash; exclude it as cost.
Checklist
- Find prepaid interest in Section F of the Loan Estimate and Closing Disclosure.
- Ask for the day-count basis and compute your own per diem: balance times rate, divided by days.
- Count the days from funding to the first of the next month and multiply. Match the disclosure.
- Confirm the old loan's payoff good-through date covers the funding date, with its own per diem noted.
- Keep prepaid interest in your cash-to-close budget and out of your break-even closing costs.
Common questions
Why do I owe interest at closing before my first payment?
Because mortgage interest is paid in arrears. Your first monthly payment covers the first full month, so the partial days from funding to that month's start are collected at closing. CFPB defines prepaid interest in exactly those terms.
How is per-diem interest calculated?
Loan amount multiplied by the annual note rate, divided by the number of days in the lender's stated basis, commonly 365. A $400,000 loan at 6.50 percent gives about $71.23 per day. Confirm the basis on your note and check the multiplication yourself.
Why did my prepaid interest change from the Loan Estimate?
The day count depends on the closing and funding dates, which move. CFPB notes this figure may change between the Loan Estimate and Closing Disclosure. A moved date, not a moved rate, is the usual cause.
Does closing at month-end save money?
It saves cash at the closing table, not interest overall. Closing late in the month means fewer prepaid days now and a first payment sooner. The interest for every day you hold the loan is owed either way.
Should prepaid interest count in my refinance break-even?
No. It is a timing item: you would owe daily interest on the old loan for those same days. Count it in the cash you need at closing, and leave it out of the true closing costs your monthly saving must repay.
Sources and verification
- Consumer Financial Protection Bureau, What are prepaid interest charges?: consumerfinance.gov Ask CFPB: daily interest between closing and the period covered by the first payment, Section F placement, and that the figure may change before the Closing Disclosure. Checked October 4, 2026.
- Consumer Financial Protection Bureau, Loan Estimate explainer: consumerfinance.gov page-by-page guide to the Loan Estimate: closing cost categories, Section A origination charges, third-party service sections, and the appraisal copy right. Checked October 4, 2026.
Educational explanation, not a quote. Your per-diem amount, day-count basis, and funding date appear on your Closing Disclosure and payoff statement, which govern your transaction.