I'd guess that if you still haven't filed your taxes then you probably haven't contributed to your 2008 IRA either. Am I right? Well it's okay because this still gives you time to open and contribute to an IRA. You can do so before the April 15th tax deadline and fortunately this gives you three more days to make it happen.
Why would you want to put money into an IRA, anyway?
Well the obvious is that IRAs have annual contribution limits. Putting money into your 2008 IRA now will allow you to still legally add money to your 2009 IRA later.
The contribution limit for 2008 was $5,000, so if you only contributed $2,000 but you have $1,000 that you'd like to add to it, you can file it under the 2008 contribution and still have the full maximum contribution available for the remainder of 2009.
You may be able to save on your taxes.
If you have a standard IRA you’ll be able to take a tax deduction for any money contributed. Roth IRAs are funded with post-tax money, so they don’t provide any deduction.
Be sure your IRA contributions are posted to the correct year before the tax deadline.