What 45 days works out to
Forty-five days is always exactly 45. "A month and a half" is not: it runs 44 to 47 days depending on the months, and six weeks is only 42. When a deadline is written as a day count, count the days — those extra three days past six weeks have decided real cases.
Calendar days vs business days
Switching to business days skips every Saturday and Sunday, so the same "45" reaches far deeper into the calendar — about nine weeks instead of six and a half.
Forty-five business days lands roughly 18 calendar days later than 45 calendar days — about two and a half extra weeks of elapsed time.
Where a 45-day deadline usually comes from
- 1031 exchange — when you sell an investment property, you have 45 calendar days to identify the replacement in writing (IRC §1031). The clock does not stop for weekends or holidays.
- IRS refund interest — the IRS has 45 days from filing to issue a refund before it must start paying you interest on the overpayment (IRC §6611).
- Mortgage escrow & force-placed insurance — under RESPA, a servicer must give at least 45 days' notice before charging for force-placed insurance, and deliver an initial escrow statement within 45 days of closing.
- Mortgage closing — a typical purchase closes in 45 to 60 days from accepted offer.
- Returns and probation — some retailers use a 45-day return window, and some employers set a 45-day trial period.
The federal-law default is calendar days
- "Days" means calendar days. In US federal rules, an unqualified "45 days" counts all seven days of the week. Weekends drop out only when the text says "business days" or "working days."
- Six weeks is not 45 days. Six weeks is 42. Treating them as equal quietly loses three days — enough to blow a hard deadline.
- The 1031 clock is unforgiving. Miss the 45th day by an hour and the tax deferral is gone; on a large property that can mean six figures in capital-gains tax.
Common questions
Is 45 days the same as a month and a half?
Not exactly. Forty-five days is always exactly 45. Six weeks is 42, and a month and a half runs 44 to 47 days depending on which months it spans. When a deadline is written in days, count the days.
How many weeks is 45 days?
Six weeks and three days (45 divided by 7 is 6 remainder 3). Rounding it down to six weeks drops three days, which can miss a legal deadline.
How long is 45 business days?
About 63 calendar days, or roughly nine weeks, since only Monday to Friday count. Public holidays are not removed unless you subtract them yourself.
Does the 1031 exchange 45-day deadline move if it lands on a weekend?
No. The 45-day identification period in a like-kind exchange is absolute. It does not extend for weekends or holidays, so the count runs straight through.
