IRS number

Under IRS rules, buying out your partner constitutes a "change of status" that requires you to get a new federal tax ID number. But because you bought him out earlier this year, there's still time to consider making your spouse or significant other a partner with a 1 percent partnership interest. That way, you'll preserve your status as a partnership and can keep your current tax ID number. Just don't "backdate" any documents, as that will get you in serious legal trouble if you're found out.