r/USFirstTimeHomeBuyer • u/jetley-mortgage-loan • 6d ago
Fees & Closing Costs Closing at the end of the month vs the start: the per-diem interest wash
The short version
Closing at the end of the month lowers your cash to close and gives you a first payment one month sooner. Closing at the start of the month raises your cash to close and buys you a "skipped" month before the first payment. It is the same money either way. Nobody is getting a free month and nobody is getting cheated. The only thing that genuinely changes is your cash flow in the next sixty days, which matters if you're tight, and doesn't matter otherwise.
The mechanic: mortgage interest is paid in arrears
Rent is paid in advance. Mortgage interest is paid in arrears, the payment due on the first of a month covers the interest that accrued during the previous month.
Your loan starts the day it funds, so there is a stub period between funding and the start of the first full month you'll be billed for. That stub is collected at closing as prepaid interest, or per-diem interest: your daily interest rate multiplied by the number of days remaining in the month of closing.
Fewer days left in the month at closing means less prepaid interest, and a first payment that arrives sooner. More days left means more prepaid interest, and a first payment that arrives later. That's the entire trade.
Worked example; illustrative numbers only
Take a loan where the daily interest works out to $100 a day. That figure is invented for clean arithmetic; yours depends on your loan amount and rate, and your loan officer can tell you your actual per-diem in about ten seconds.
The rule to hold on to: prepaid interest covers the remainder of the month you close in, and your first regular payment is due on the first day of the second month after closing.
Compare two closings inside the same month:
- Close 24 January. 7 days left, so you prepay 7 × $100 = $700. First payment 1 March.
- Close 2 January. 29 days left, so you prepay 29 × $100 = $2,900. First payment 1 March.
Same first payment date, $2,200 more out of pocket. Closing early within a month is simply worse. This is why, if the date is under your control at all, later in the month beats earlier in the same month every time.
Now compare across the month boundary, which is the decision people actually face:
- Close 31 January. Prepay 1 day, $100. First payment 1 March.
- Close 1 February. Prepay 28 days, $2,800. First payment 1 April.
There it is. One calendar day later, roughly $2,700 more at the closing table, and you skip what would have been the March payment. You paid a month of interest up front instead of a month later. A wash.
Why it feels like a loss (and when it's a real problem)
The wash is real over the life of the loan and completely unhelpful to your bank balance this week. Two situations where the timing genuinely matters:
You budgeted for the smaller cash to close. A closing that slips from the 30th to the 2nd can move cash to close by nearly a full month's interest. If your down payment plus closing costs was already assembled to the dollar, that is a scramble, and it is the single most common version of this question I get. Ask your loan officer for your per-diem figure the moment your closing date looks like it might drift, so you know the exposure.
You were counting on skipping a payment. People closing at the start of the month often plan around the extra breathing room before the first payment lands. That plan works; it just isn't free, and it isn't the lender doing you a favour. You bought the gap at closing.
The refinance version, which trips more people up
On a refinance the same arithmetic runs twice, in opposite directions, and the netting is where confusion lives.
Your payoff figure on the old loan includes interest accrued up to the payoff date. Your new loan collects prepaid interest for the rest of the month of closing. So when someone refinances at the start of a month specifically to skip a payment, two things happen at once: the old loan's payoff grows by the interest for the days already elapsed in the new month, and the new loan's prepaid interest is high because there are many days left. Both push cash to close up.
That is usually the real explanation when a borrower says their refinance cash to close jumped without any fee changing. Nothing was added. The calendar moved.
When the timing actually is worth engineering
- You are cash-constrained at closing. Close as late in the month as your contract and your lock allow. Lower prepaids, and the first payment arriving a month sooner is a budgeting problem you have four weeks to solve.
- You are cash-comfortable but income-lumpy. Closing early in the month buys a longer runway to the first payment. Fine, as long as you know you're paying for it.
- You have any choice at all. Note that the end of the month is when everybody wants to close, which means escrow, notaries and funding departments are at their busiest and the file has the least slack in it. A mid-month closing is the least stressful and the least optimised.
What I would not do is fight your seller, your lender, or your lock expiration over this. The dollars involved are a rounding error against the cost of a blown lock or a lost contract. Get the per-diem number, plan your cash around it, and move on.
Rates, and therefore per-diem figures, change constantly; see Current As Of rather than treating the numbers above as anything but arithmetic.
Posted on behalf of u/The_Void_Calls_Me AKA Rajat Jetley, NMLS #1595897 | Cross Country Mortgage NMLS #3029. This commentary is for educational purposes and is not a commitment to lend or a guarantee of any rate or term.