The Opportunity Zone 180-day investment rule

You have 180 days. Section 1400Z-2(a)(1)(A) allows deferral only for an amount invested in a Qualified Opportunity Fund (QOF) during the 180-day period that begins on the date of the sale or exchange that produced the gain.¹ A QOF is a corporation or partnership that self-certifies on Form 8996 and holds at least 90% of its assets in Opportunity Zone property.²

The regulations define the period as the 180 days beginning on the day the gain would be recognized for federal income tax purposes if you did not elect to defer it.³ Because the period begins on that day, the recognition date counts as day 1 and the last day to invest is 179 days later. Count carefully and do not plan a closing for day 180; wires, subscription documents and fund acceptance all take time.

Each eligible gain has its own window. If you sell three properties in a year, you have three 180-day periods, and you can invest each gain in the same QOF or in different QOFs, in full or in part. The overview of eligible gains covers which gains count.

For most gains the clock starts on the sale date, but the regulations give special start dates for §1231 gains, pass-through gains, installment sales and fund dividends.^3,4

Section 1231 gains get their own treatment because they are netted at year-end to decide whether they are capital or ordinary. The regulations sidestep that: the gross §1231 gain is eligible and its window runs from the sale date.^4,5 See Section 1231 gains and Opportunity Zones.

Pass-through owners get the most flexibility. If a partnership, S corporation, estate or non-grantor trust does not invest its gain in a QOF itself, each owner can defer its share, and its window starts by default on the last day of the entity's tax year. The owner may instead elect the entity's sale date or the due date of the entity's return without extensions, which is March 15 for a calendar-year partnership.^6,7 The K-1 gains guide walks through each option.

You must acquire an equity interest in an entity that is a QOF at the time of the investment, within the window, and then make the deferral election on your return.^8,9

• Equity only. The qualifying investment is stock in a QOF corporation or an interest in a QOF partnership. A loan to the fund does not qualify.
• The fund must be a QOF. An entity self-certifies on Form 8996 and names the first month it is a QOF; money contributed before that month is not a qualifying investment.²
• Cash is the normal method. The regulations also permit contributions of property, with rules that can limit the qualifying amount, so property contributions need specific advice.
• Buying an existing QOF interest from another investor can also be a qualifying investment if it is done within your 180 days.
• Only the gain needs to be invested. Your original basis in the sold asset does not have to go into the fund.

Commitments are not investments. If a fund calls capital over time, only the amounts actually contributed within your window qualify. That is why most QOFs that build large projects take the investor's full gain at one closing and hold the cash at the business level under the working capital safe harbor, which allows up to 31 months per written plan and up to 62 months in total.¹⁰

A gain realized in 2026 and invested in a QOF on or after January 1, 2027, within its 180-day window, receives the rules for amounts invested after December 31, 2026: a five-year deferral and a 10% or 30% basis step-up.^11,12

The statutory effective date turns on when the amount is invested in the QOF, not when the gain was realized.¹² Any gain recognized on or after July 6, 2026 has a 180-day window that reaches January 1, 2027. A gain recognized today, October 20, 2026, can be invested through April 17, 2027.

Timing matters in the other direction too. An amount invested on or before December 31, 2026 does not get the rules described on this site; under the statute, gain deferred by such an investment is included in income on December 31, 2026, so a late-2026 investment provides essentially no deferral.¹³ Notice 2026-40 also says gain included on that date cannot be deferred again in a new QOF investment.¹²

You elect deferral on Form 8949, attached to a timely filed return for the year the gain would have been recognized, and you file Form 8997 each year you hold the investment.^9,14

On Form 8949 you report the sale as usual, then report the deferral as a separate line with the QOF's EIN and the investment date, entering the deferred amount as a negative adjustment.⁹ Form 8997 then tracks the deferred gain from year to year, including what you held at the beginning and end of each year and any dispositions.¹⁴

Because the 180 days can run past April 15, many investors file on extension or amend after investing. A partner using the return due date window for a 2027 partnership gain could invest as late as September 2028, after the partner's own 2027 return is due; the election belongs on the 2027 return, so the partner should extend or plan to amend. See Form 8996 and Form 8997.

If you miss the window, that gain cannot be deferred, and the amount you invest becomes a non-qualifying investment with no Opportunity Zone tax benefits.¹

There is no general late-investment relief in the current rules. Check, though, whether another start date is available. A partner who missed the sale-date window may still be inside the year-end or due-date window. An installment seller may have new windows with each payment. The checklist below catches the common errors.

Data center projects need capital for years, but each investor's money must go in within that investor's 180 days, so funds collect equity in closings and the QOZB manages the long build with the working capital safe harbor.¹⁰

Two groups see this most often. Landowners who sell sites to data center developers usually have §1231 or capital gain with a sale-date window, so they should line up a QOF before closing the land sale. See Opportunity Zones for landowners. Investors in a sponsor's fund should expect a closing schedule built around their windows, with cash deployed under a written plan as power, permits and construction milestones arrive. For how that plays out, see data center power timelines and the Opportunity Zone clock.