California Registered Domestic Partners (RDPs) and married same-sex couples probably have become used to the oddities of their status when filing their income taxes.  For State income tax, they have had the choice of Married/RDP Filing Separately or Married/RDP Filing Jointly (Franchise Tax Board Publication 737).  Since the Federal government does not recognize these unions, they can use only the single filing status, or if they qualify, the head of household filing status (IRS Publication 555).  This means extra cost, like having to pay a tax return preparer for the added time of computing tax owed under two different filing statuses for each partner, or having to purchase two Turbo Tax programs.  For the current tax season, the IRS has tweaked its rules in the publication cited above, which was revised in December and posted last week.  For 2010, these couples still must file as single people, but each partner is now required to report half of their partner's income (as defined by the Community Property rules in the same publication) on their single filing status return.  Just to help to keep things straight, and to prevent IRS auditors from stressing to figure out where this "extra" income came from on a single filing status return, the helpful publication suggests, "[Y]ou may want to write the social security number of your partner or same-sex spouse in the 'Notes' section of the worksheet to avoid delays in the processing of your return." Oh well. Finally making it to the "Notes" section of a worksheet might be viewed as some kind of progress for life partners.  Altruism, or did the IRS figure out they could be pulling in more cash?  [BB]