A company you hold announces it is separating a division into an independent business. On the distribution date, shares in the new entity appear in your account alongside your existing holding.
Nothing was sold and nothing was bought. In a qualifying spin-off no tax is due — and your cost basis, which was attached to one holding, must now be split between two.
Getting that allocation wrong means paying the wrong tax when you eventually sell, in one direction or the other.
What changed in 2026
- Corporate separations remained common. Large companies continued to break into focused entities.
- Broker basis reporting improved and stayed imperfect. Allocation errors continued to appear, particularly for shares transferred between brokers.
- Company disclosure got more accessible. Allocation ratios became easier to find in investor materials.
- The underlying rules were unchanged. Tax-free reorganisation treatment is long-standing.
Why it is not taxable
A qualifying spin-off is treated as a continuation of your existing investment rather than as a disposal. You held an interest in a business; that business divided; you now hold interests in both parts.
Because your economic position is substantially unchanged, no gain is recognised. The conditions for qualification are technical — concerning the business purpose, the degree of control distributed, and continuity requirements — and the company will state whether the transaction is intended to be tax-free.
Where a transaction does not qualify, the distribution may be taxable as a dividend. Companies disclose this, and it is worth reading rather than assuming.
Allocating basis
Your original basis in the parent shares is divided between the parent and the spun-off shares, in proportion to their relative values immediately after the separation.
The company publishes the allocation percentages, typically in a tax information notice on their investor relations pages shortly after the distribution. Those figures are what you should use.
|
Before |
After |
| Holdings |
Parent only |
Parent plus spin-off |
| Total basis |
Original amount |
Same total, split |
| Basis per holding |
All in parent |
Allocated by published ratio |
| Holding period |
Original |
Carries to both |
The holding period carrying over to both holdings matters: shares in a company that has existed for weeks may nonetheless be long-term in your hands, because your holding period in the parent transfers.
That is easy to get wrong if you assume the new shares started fresh — and it changes the rate on a sale.
Where errors arise
Broker allocation. Brokers generally apply the published ratio, and errors occur — particularly for positions transferred between brokers, where basis information may be incomplete or was never correctly transferred.
Checking your broker's allocation against the company's published figures after a spin-off takes a few minutes and prevents a wrong gain calculation years later.
Cash in lieu of fractional shares. Spin-off ratios rarely produce whole numbers, so brokers sell fractional entitlements and distribute cash. That cash is a taxable sale of a fractional share, with its own small gain or loss.
The amounts are trivial and they are reportable, and mismatches between what you report and what was reported for you cause correspondence out of proportion to the sums involved.
Multiple lots. If you bought the parent shares across several purchases, the allocation applies to each lot separately, preserving their individual bases and holding periods. Software handles this; manual tracking frequently does not — see tax lot selection.
Common mistakes
- Assuming the new shares have zero basis. Basis is allocated, not created.
- Not checking the broker's allocation. Errors happen, especially after transfers.
- Treating the new shares as short-term. The holding period carries over.
- Ignoring cash in lieu. Small and reportable.
- Not saving the company's tax notice. Needed years later when you sell.
- Applying the ratio to a total rather than per lot. Loses lot-level detail.
- Assuming every spin-off is tax-free. Some are not; check the disclosure.
FAQ
Where do I find the allocation ratio?
The company's investor relations site, usually in a tax information document published after the distribution. Save it; you will need it when you eventually sell.
What if I sell one of the holdings immediately?
Perfectly permissible, and the gain is computed against the allocated basis with the carried-over holding period. That frequently means long-term treatment on shares you have held for days.
Does this apply to a merger or acquisition?
Different transactions with their own rules. Stock-for-stock mergers frequently receive similar non-recognition treatment; cash consideration is generally taxable.
What about a rights offering or a stock dividend?
Related corporate actions with their own basis treatment. Each has specific rules, and the company's disclosure is the starting point.
Where to go next
For basis mechanics generally, read cost basis explained. For choosing which lots to sell afterwards, tax lot selection, and for the rates on eventual sale, capital gains tax explained.
This is general information, not tax advice. Corporate action treatment depends on the specific transaction; consult the company's disclosure and a qualified preparer.