Can I split the capital gains exemption between my spouse and me on the same business sale?

Not by simply dividing one gain in half after the fact — the exemption is personal to whoever actually realizes a capital gain on their own qualifying shares, so you can't just assign part of your gain, or part of your exemption room, to your spouse after you've already agreed to sell. What can work is having each spouse personally own qualifying shares before the sale process begins, so that each of you realizes your own separate capital gain on your own shares, and each can apply your own exemption against your own gain.

This generally requires planning well ahead of a sale, such as having shares issued to, or transferred to, a spouse early on (subject to its own tax considerations at that time), rather than trying to restructure ownership once a buyer is already at the table. A family trust holding shares for multiple family members, including a spouse, is another common structure used to spread a gain — and potentially multiple exemptions — across more than one person, though the trust and its beneficiaries each need to independently meet the qualifying conditions.

Because timing and structure both matter enormously here, this needs real advance planning with a tax advisor and a lawyer, not a decision made during the sale negotiation itself.