Section 1045 QSBS Rollover: 60 Days to Postpone Capital Gain Into New QSBS

Section 1045 is the capital gain rollover for qualified small business stock. The IRS states it plainly: "You may qualify for a tax-free rollover of capital gain from the sale of qualified small business stock held more than 6 months."^[1] The gain is not forgiven; it is postponed. The basis of the replacement QSBS is reduced by the deferred amount, so the number comes back into income the year the replacement stock is finally sold.^[4]

The mechanics are tight. The replacement stock has to be bought during the 60 day period beginning on the date of the sale, it has to itself be QSBS, and it has to continue to meet the active business requirement for at least the first 6 months after purchase.^[2] Miss any one of those tests and the rollover is not available for that trade. For a founder sitting on a long-held QSBS position who wants to reposition into another early-stage company without triggering an immediate tax bill, the election is the mechanism. For planning questions on when to use it, see our advisory solutions work.

Section 1045 is open to a taxpayer other than a corporation. The IRS points at the three most common pass-through holders explicitly: "A pass-through entity (a partnership, S corporation, or mutual fund or other regulated investment company) may also make the choice to postpone gain."^[6] Ownership continuity matters in those cases: the postponed gain flows to a partner, shareholder, or fund owner only if that person held an interest in the entity for the entire period the entity held the QSBS.^[6]

There is a second path at the owner level. If a pass-through sold QSBS held more than 6 months and the owner held an interest for the entire period, the owner, rather than the entity, may buy the replacement QSBS within the 60 day window and elect at the owner level.^[6] For partners, that election is reported through Schedule K-1 (Form 1065), and Regulations section 1.1045-1 governs the partnership mechanics.^[8] C corporations are outside Section 1045 by statute, which is one reason the entity-choice conversation for a growth company usually ends with business tax return preparation on the C corporation side and a advisory solutions decision on the shareholder side.

QSBS is defined under Section 1202, and Section 1045 borrows that definition. The IRS tests for QSBS run through five requirements the stock has to meet: it must be stock in "a C corporation (that is, not S corporation stock)", it must have been "originally issued after August 10, 1993", the corporation must have been a qualified small business as of the issuance date, the taxpayer must have acquired the stock at its original issue, and during substantially all the time the taxpayer held the stock the corporation was a C corporation and "at least 80% of the value of the corporation's assets were used in the active conduct of one or more qualified businesses".^[9]

The gross asset test moved under the One Big Beautiful Bill. The IRS now phrases the ceiling as "$75 million ($50 million if the stock was issued on or before July 4, 2025) or less" at every moment from August 9, 1993 through the issuance of the stock, and immediately after.^[9] Service businesses in health, law, engineering, accounting, actuarial science, performing arts, consulting, athletics, financial services, and brokerage are explicitly outside the "qualified business" definition, as are banking, insurance, financing, farming, extraction, and hotel or restaurant operations.^[9] That is a surprisingly short list of eligible profiles, which is why a candidate for Section 1045 is almost always a software, hardware, or product company; a professional services tax help firm, by contrast, is usually out at the first test.

The 60 day window is strict. The IRS writes it twice, once in the general rules and once in the Form 8949 instructions, both saying the clock begins on the date of the sale.^[2][8] That start date matters because the rollover tests the quantity of replacement QSBS bought within those 60 days against the amount realized on the sale: anything bought outside that window is irrelevant to this trade. The clock does not pause for closing complications; it does not pause for a partnership distribution; and the rollover takes into account only replacement QSBS that was not already used to cover an earlier rollover for the same seller.^[3]

The window also does not care about the market side of the trade. The replacement company may be a brand new issue or a secondary private round, but the stock has to be acquired at original issue to be QSBS, which rules out most secondary purchases. For a reader who has sold the first position and is still shopping the replacement, the first conversation to have is with the issuer about the issuance mechanics, because the sixty-day clock is already running the day the first trade settles.

The basis adjustment is the economic trade in Section 1045: the deferred gain is not erased, it is reserved against future recognition. The IRS writes it in one line: "You must subtract the amount of postponed gain from the basis of your replacement stock."^[4] If a seller rolls the entire gain into replacement QSBS whose cost equals the amount realized, the replacement stock sits on the books at a basis equal to its cost reduced to the amount of after-rollover equity, and the gain is realized when the replacement is sold later.

The holding period is slightly different. The IRS allows the holding period of the stock sold to tack onto the replacement stock "except for the purpose of applying the 6-month holding period requirement for choosing to roll over the gain on its sale".^[5] In plain language: the clock from the first stock counts toward the Section 1202 five-year window on the replacement, but when the time comes to roll over the replacement under Section 1045, the replacement has to stand on its own 6 month holding period. That split rule is one reason to coordinate every rollover decision with advisory solutions, because it changes which exit windows are available on the replacement company.

The computation is simpler than it reads at first. The IRS defines the recognized amount as "The amount realized on the sale, minus The cost of any qualified small business stock you bought during the 60-day period beginning on the date of sale (and did not previously take into account on an earlier sale of qualified small business stock)."^[3] The result is the floor on current-year recognition: if that number is less than the capital gain, the balance is postponed; if it equals or exceeds the gain, no deferral is available for the trade.^[3]

The asymmetric wording matters. The rollover does not deliver a tax-free trade whenever the proceeds are reinvested; it only shelters the piece covered by the replacement cost. A reader whose sale throws off more proceeds than are committed to replacement QSBS during the window picks up current-year gain equal to that uncovered piece, with the remaining gain postponed into the replacement basis. The dollars that stayed in cash are not sheltered, and the Section 1202 exclusion remains the planning backstop on any amount that cannot be rolled.

The election rides on the regular capital-gain reporting path. The IRS instruction is a single run of sentences: "Report the entire gain realized from the sale in Part I or Part II of Form 8949. To make the election to postpone gain, report the gain as you would if you were not making the election. Enter "R" in column (f). Enter the amount of the postponed gain as a negative number in column (g)."^[7] No separate statement attaches to the return; the code letter and the negative amount are the election.

Timing of the election is tight. The IRS allows the choice to be made no later than the due date (including extensions) for the return for the year the stock was sold, and gives one safety valve: an amended return filed no later than 6 months after the original due date (excluding extensions), with "Filed pursuant to section 301.9100-2" at the top of the amended return.^[7] After that window, the deferral is lost even if every other test is met. For a founder who sold in December, that means the clock on the election closes on the extended due date of the following April 15 return, not on the 60 day window for buying the replacement stock.

The two sections are complementary, not alternatives. Section 1045 postpones; Section 1202 excludes. The IRS allows up to 50% exclusion on QSBS acquired before February 17, 2009, up to 75% for QSBS acquired between February 17, 2009 and September 27, 2010, and up to 100% for QSBS acquired after September 27, 2010.^[10] All of those apply only to QSBS held more than 5 years, so a position sold at the 6 month mark cannot ride the exclusion yet and that is exactly where the rollover carries the ball.^[9]

The per-issuer cap under Section 1202 is "the greater of: Ten times your basis in all qualified stock of the issuer you sold or exchanged during the year; or $10 million ($5 million for married individuals filing separately), minus the amount of gain from the stock of the same issuer you used to figure your exclusion in earlier years."^[11] A clean rollover under Section 1045 keeps a bigger piece of a potential future gain inside the exclusion by preserving the tacked holding period into the five-year test. For high-dollar exits, see our full treatment of the QSBS exclusion in the Section 1202 QSBS exclusion under OBBB.

The failures we see cluster into a short list. The replacement company turns out not to be a C corporation on the issuance date, or is formed as an LLC taxed as a partnership and converts later; neither path produces original-issue QSBS. The replacement passes QSBS on day one but blows the "active business" requirement in the first 6 months by sitting on investment capital, which is a problem the IRS flags inside the rollover rules themselves.^[2] The replacement company's gross assets have crossed the current $75 million or legacy $50 million ceiling before the stock is issued, which is a fatal strike at issuance.^[9]

Paperwork breaks the rollover almost as often as the economics do. The seller buys the replacement one day past the 60 day window, and the trade is out even by hours. The partnership mechanics are missed because the ownership continuity requirement is not documented, and the deferral then flows to the wrong partner.^[6] The amended return under section 301.9100-2 is filed after the 6 month safety valve closes.^[7] Each of those failures is unrecoverable for that trade, which is why the right time to involve an Enrolled Agent is before the first stock is sold.

The immediate consequence is the loss of deferral: the full capital gain on the original QSBS sale is recognized in the year of sale, including any long-term capital gain rate and the Net Investment Income Tax surtax if the seller's income clears the thresholds. For a founder exiting at the 6 month mark whose position has an unrealized Section 1202 exclusion that is not yet available, that current recognition can be the entire difference between the rolled position's future 100% exclusion and a current-year all-cash tax hit.

There is a second quiet consequence. A failed rollover does not re-start the holding period on any replacement stock that was already bought; the replacement sits in the portfolio without the tacked holding period and often without the active-business facts needed for its own Section 1202 window. In the worst case, the seller realizes the gain now and loses the rollover protection on both ends of the trade. That is the scenario a prepared Enrolled Agent is paid to prevent, and it is the entire reason we treat this election as a planning engagement, not a return-season checkbox. Our business tax return preparation work handles the return mechanics; our advisory solutions work is where the rollover decision gets made.