> Apple generally makes security updates for macOS available for three years after release. So Intel hardware under macOS 26 Tahoe should linger at least until late 2028.
This time around, there's no "generally" or "should" required, as Apple has taken the rare step of explicitly stating it:
> macOS Tahoe will be the last release for Intel-based Mac computers. Those systems will continue to receive security updates for 3 years.