A spin-off and a split-off both carve a subsidiary out of a parent company and float it as its own public stock, but they reach you as a shareholder in very different ways. In a spin-off, the parent hands every shareholder a proportional amount of the new company’s stock automatically, and you end up owning both. In a split-off, the parent runs a tender offer inviting you to swap some or all of your parent shares for subsidiary shares, and you choose whether to participate. The split-off vs spin-off distinction shapes what shows up in your account, what you have to decide, and how your cost basis gets rewritten for tax purposes.
What a Spin-Off Does to Your Holdings
A spin-off is passive on your end. The parent company picks a record date, and every shareholder on that date receives shares in the subsidiary in proportion to their existing stake. Own 1% of the parent, receive 1% of the distributed subsidiary shares. You sign nothing, elect nothing, and pay nothing. The new shares simply appear in your brokerage account.
After the distribution, you hold stock in two separate public companies. Your parent-company share count is unchanged, though the parent’s share price typically drops to reflect the value it just shed. The subsidiary starts trading independently with its own board and management. One position becomes two, without any cash changing hands.
What a Split-Off Asks of You
A split-off is structured as a tender offer. The parent invites shareholders to exchange some or all of their parent stock for subsidiary stock, and participation is voluntary. Because not everyone takes the offer, the distribution isn’t proportional across the shareholder base: some investors swap in, others keep their parent stock, and the two companies end up with different owners.
To make the exchange attractive, the parent usually builds in a premium so that each tendered parent share converts into slightly more than a dollar of subsidiary stock. In the 2023 Johnson & Johnson separation of Kenvue, participating shareholders received roughly a 7% discount on the exchange ratio.
If more shareholders tender than the parent needs, the offer is oversubscribed and gets prorated. The company accepts only a fraction of what each participant tendered, applied evenly. In the JNJ/Kenvue exchange, the final proration factor was about 23.2%, so roughly a quarter of the tendered shares were actually accepted.1Johnson & Johnson. Johnson and Johnson Announces Final Results of Exchange Offer and Finalizes Separation of Kenvue Inc Anything not accepted is returned to your account.
For the parent, a split-off works like a buyback. The tendered shares get retired, and total shares outstanding go down. That’s a real difference from a spin-off, where the parent’s share count stays the same.
How Your Cost Basis Changes
The tax bookkeeping is where the two transactions diverge most for shareholders.
After a Spin-Off: Allocate Across Two Stocks
Because a spin-off adds new stock without taking anything away, your original cost basis has to be split across the two holdings. The tax code treats the spin-off as if you surrendered your parent shares and received back both the parent stock and the subsidiary stock, then requires you to spread your total basis across everything you now hold.2Office of the Law Revision Counsel. 26 USC 358 Basis to Distributees
The allocation is based on relative fair market values immediately after the separation. If the parent represents 70% of the combined post-separation value and the subsidiary represents 30%, then 70% of your old basis attaches to the parent shares and 30% moves to the subsidiary shares. Your total basis doesn’t change; it just sits in two buckets, and the per-share basis of both stocks is lower than your original per-share basis in the parent.
Companies are required to file IRS Form 8937 reporting the effect of the separation on shareholder basis, including the data behind the allocation calculation.3Internal Revenue Service. Instructions for Form 8937 Most parent companies publish it on their investor relations page shortly after the separation. If your broker doesn’t adjust your basis automatically, the Form 8937 gives you the percentages you need to do it yourself.
After a Split-Off: Substitute the Basis
The split-off math is cleaner. Because you actually surrendered specific parent shares in exchange for subsidiary shares, the basis of the new subsidiary stock equals the adjusted basis of the parent stock you gave up.2Office of the Law Revision Counsel. 26 USC 358 Basis to Distributees No proportional allocation. If you tendered parent shares carrying $5,000 of basis, your new subsidiary shares carry a $5,000 basis. Any parent shares you kept keep their original basis untouched.
Your Holding Period Carries Over
If you’ve held the parent stock for more than a year, the holding period on the new subsidiary shares carries over from the parent stock. Under Section 1223, when stock received in a Section 355 distribution takes its basis (in whole or in part) from stock you already held, the holding period of the new shares includes the time you held the old ones.4Office of the Law Revision Counsel. 26 US Code 1223 – Holding Period of Property
So if you bought the parent three years ago and receive subsidiary shares today through either a spin-off or a split-off, those new shares are already long-term. A subsequent sale qualifies for long-term capital gains rates. The clock doesn’t restart.
Tax-Free Treatment and When It Isn’t
Both spin-offs and split-offs are engineered to qualify as tax-free under Section 355 of the Internal Revenue Code. When the requirements are met, neither the corporation nor its shareholders recognize gain or loss on the distribution or exchange.5Office of the Law Revision Counsel. 26 US Code 355 – Distribution of Stock and Securities of a Controlled Corporation The statute applies whether the distribution is proportional (spin-off) or shareholders surrender stock (split-off).
Qualifying isn’t automatic. Section 355 imposes a long list of conditions the parent company has to satisfy, covering things like continuous control of the subsidiary, an active business history of at least five years on both sides, a real business purpose, and limits on prearranged acquisitions of either company within a four-year window around the distribution. Those are corporate-planning concerns, but the consequences reach shareholders: if the structure fails, a spin-off becomes a taxable distribution and a failed split-off is treated as a stock redemption, with gain or loss measured against the surrendered basis.6Office of the Law Revision Counsel. 26 USC 356 Receipt of Additional Consideration For any separation of a major company, the parent’s SEC filings and investor materials will spell out whether tax-free treatment is expected.
Cash for Fractional Shares Is Still Taxable
Distribution ratios rarely land on whole numbers. If a spin-off ratio entitles you to 47.3 subsidiary shares, you’ll receive 47 shares plus a small cash payment for the 0.3 fractional share. The company bundles all the fractional entitlements, sells them, and distributes the proceeds.
That cash is taxable even in an otherwise tax-free separation. When an exchange includes money or property beyond the permitted stock (known as “boot”), the shareholder recognizes gain up to the cash received.6Office of the Law Revision Counsel. 26 USC 356 Receipt of Additional Consideration For a fractional-share payment, you’d report a small capital gain calculated using the allocated basis for that fraction. The amount is usually minor, but skipping it can cause problems when the IRS matches the 1099-B your broker files.
Side-by-Side Comparison
- What you have to do: A spin-off requires nothing from you. A split-off requires you to decide whether to tender your parent shares.
- What you end up owning: After a spin-off, you hold shares in both companies. After a split-off, you hold shares in one company or the other, or a mix if you tendered only part of your position.
- Effect on parent shares: A spin-off leaves the parent’s share count unchanged. A split-off retires the tendered shares, reducing the parent’s outstanding stock.
- Cost basis: A spin-off requires you to allocate your original basis by relative market value across two stocks. A split-off substitutes the basis of the surrendered parent shares directly into the new subsidiary shares.
- Holding period: Both let the parent’s holding period carry over to the new shares.
- Oversubscription risk: Only split-offs carry the risk that your tender is prorated because too many shareholders wanted in.
- Exchange premium: Split-offs frequently offer a premium to attract participation. Spin-offs distribute at market value with no premium.
Which structure a company uses is the company’s call, not yours. What matters on your end is knowing how the transaction reshapes your portfolio, how it rewrites your cost basis, and whether it qualifies as tax-free. Once the separation closes, the parent’s Form 8937 filing and investor relations materials will give you the specific percentages and numbers you’ll need at tax time.