First-Time Homebuyers' Tax Credit Act of 2009 - Amends the Internal Revenue Code to allow an individual taxpayer who qualifies as a first-time homebuyer (i.e., an individual who had no ownership interest in a principal residence within the past two years) a one-time refundable credit for up to $20,000 of the purchase price of a principal residence. Reduces such credit for taxpayers with adjusted gross incomes exceeding $75,000 ($150,000 for married couples filing jointly).