I received a notice from the IRS demanding taxes due, penalties and interest for return not filed for tax year 2005. I thought I had filed for all previous years and was very surprised that this year was missed. I used an online tax service to fill out and prepare my tax return for 2005 and sent it in. This tax return included a refund due to me of $4357.00. Today I received a letter from the IRS stating that they did not have to pay the refund because it had been more than 3 years since the return was due (April 15, 2006). They did not dispute the return, they simply said they did not have to pay it. Is it true that they can hunt me down until the day I'm dead if I owe them money but I only have 36 months to collect money they owe me or they're off the hook?