If the dividend is paid in cash, ordinary income tax rates would apply. If the dividend is paid in shares of the spin-off, it could be treated as a return of capital and taxed as long-term capital gains, which may or may not depend on how long the shares the dividend is based on are owned.

No point in trying to figure this out now, since we don't even know how they will do the payout when it comes. I have some experience in taxes, so I'll be able to answer questions when the dividend payout happens, and refer investors to the specific publication and/or tax code treatment of the dividend. Since it's likely going to be in 2015, we will have an entire year to figure out the tax consequences.