How this instrument works
This calculator counts forward exactly 45 calendar days from a start date you choose — today, by default — using the same civil-calendar arithmetic as the rest of this site's date tools, and returns the resulting date along with its day of the week.
Forty-five days is best known as the identification deadline in a Section 1031 like-kind exchange: under IRS rules, an investor who sells real estate and wants to defer capital-gains tax by reinvesting in similar property must identify the replacement property within 45 days of the original sale. Missing that date by even one day can disqualify the exchange.
The same 45-day span turns up elsewhere too — some option and due-diligence periods in real-estate contracts, and various administrative deadlines, are commonly quoted in the same round number. This tool handles the arithmetic for any of them; it doesn't advise on which deadline applies to your situation.
- Enter the date the clock starts — for a 1031 exchange, that's the closing date of the relinquished property.
- Leave the day count at 45, or edit it for a different span.
- Read the resulting date and day of the week beneath the inputs — that's the deadline date.
- Enter a negative day count to find a date 45 days before the start date instead of after.
Worked example — a 1031 exchange identification deadline
An investor closes the sale of a relinquished property on July 29, 2026. Under Section 1031, they have 45 calendar days to identify replacement property in writing. Enter 2026-07-29 as the start date and keep the day count at 45: the result is 2026-09-12, a Saturday — the last calendar day the identification can be made.
Starting instead from January 1, 2026, the same 45-day count lands on 2026-02-15, a Sunday. This calculator does date arithmetic only, not tax advice — always confirm exact deadlines and any business-day rules with a qualified professional before relying on them for a real transaction.
Questions
Is the 45-day 1031 identification period calendar days or business days?
Calendar days — all 45 days count, including weekends and holidays, with no extensions if the deadline falls on a weekend. This calculator counts calendar days accordingly; always verify the exact rule against current IRS guidance or a qualified tax advisor before relying on it for a real exchange.
What happens if I miss the 45-day identification deadline?
Missing it generally disqualifies the like-kind exchange, meaning the transaction may no longer qualify for capital-gains tax deferral. This calculator only handles the date arithmetic — for anything involving real money or tax consequences, confirm the specifics with a qualified tax professional.
Does the 45-day period start on the closing date or the day after?
Under IRS rules, the 45-day identification period begins on the day the relinquished property closes, and that day counts as day one. Enter the closing date as the start date here to match that convention.
Can I use this for something other than a 1031 exchange?
Yes — it's plain 45-day arithmetic and works for any deadline quoted that way, such as certain option periods or administrative filing windows. The 1031 exchange is simply the most common reason people search for a 45-day calculator specifically.
Does this account for leap years?
Yes. The date arithmetic runs on the civil (Gregorian) calendar, so a leap day falling within the 45-day span is already included in the result.