Worried about an IRS audit? Well this advice from Kiplinger may just put your fears to rest. It's been know that if the IRS does not initiate an audit, three years after the date of return.
So if you failed to file or record anything, you could get away with it, but the other reason's not to toss a tax return has to do with social security benefits, depreciation on home office, rental and business equipment, home mortgage and disability insurance. It can also maybe one day back you up from identity theft.
If you need to re-order tax returns from the IRS, you can do so using form 4506 at a current cost of $57- each. You decide if you want to keep them or not.
Form 4506
Link