The 45 & 180-Day Rules Explained

The two deadlines are the heartbeat of every 1031 exchange, and they trip up more people than any other part of the process. The rules themselves are simple — the mistakes come from misunderstanding when the clocks start and how they overlap. Here’s exactly how they work.

Both clocks start on the same day

When your relinquished property closes, that day is Day 0. From that single point, both deadlines begin at once — not one after the other:

• Day 45 — the identification deadline: your last day to name your replacement property in writing.
• Day 180 — the exchange deadline: your last day to close on it.

It’s 180 days total, not 45 + 180. The 45-day window sits inside the 180. After you identify, you have whatever time is left — up to day 180 — to close.

The 45-day identification rule

By the end of day 45 you must identify your replacement candidates in a signed writing delivered to your Qualified Intermediary. The description has to be unambiguous — a street address or legal description, not "a duplex somewhere in Austin." Once day 45 passes, your list is locked.

You can name more than one property, but you’re bound by one of three counting rules: the 3-property rule (up to three, any value), the 200% rule (any number, total value under twice what you sold), or the 95% rule (any number and value, but you must acquire 95% of it). Most people use the 3-property rule. Over-identifying under the wrong rule can void the entire identification — read how many properties you can identify.

The 180-day exchange rule

You have 180 calendar days from closing to receive your replacement property. There’s one easy-to-miss catch: your exchange must also be done by the due date of your tax return (including extensions) for the year of the sale. Sell late in the year and an April 15 due date can arrive before day 180 — cutting your window short unless you file an extension.

Selling in, say, December? Talk to your CPA about filing a tax-return extension so you keep the full 180 days instead of being capped at your filing deadline.

The traps to avoid

• Assuming weekends or holidays don’t count — they do, with no grace period.
• Identifying vaguely — the description must be specific and in writing.
• Waiting until day 44 with a single target — line up backups and identify early.
• Forgetting the tax-return-due-date cap on a late-year sale.

The best defense is simply to see your dates clearly and start early. Map your exact deadlines with our free deadline calculator, and when you’re ready, begin your exchange — we track both clocks for you and let you revise your identified list any time up to day 45.