First things first: Keep your copy of the tax return forever. You never know when it'll come in handy. Remember that, in many cases, the IRS destroys the original returns after four or five years. It's always best to have your copy to fall back on.
Cancelled checks, deposit statements, and receipts should generally be kept for at least three years -- seven years is best, though. Note, though, that if a receipt is for something that won't appear on your tax return for several years (such as home improvements), then you'll want to hang on to it for at least three to seven years beyond when it appears on your return.
Stock trade confirmation receipts/statements should be kept for at least three years after both ends of the transaction (both buy and sell) have closed. Again, keeping them for five or seven years is even better.
Keep proof of improvements to your property until at least three years (preferably seven) after the sale of the property, to prove your basis in the property when it is sold. This is true for rental property, investment property, and even your own personal residence.
Remember when you put that new roof on your rental property in 1987? Well, you'd better still have that receipt -- and keep it with receipts for the other improvements to that property for at least three years after you sell it. In cases like this, it is very possible that you'll have records 10, 20, 25 years old or older. It's not uncommon -- if you're retaining your records appropriately.
Keep escrow closing documents a minimum of three years after the property is sold. You'll want to retain both the purchase escrow and sales escrow statements. Much like your stock confirmation statements, you'll need to show both sides of the transaction and be able to prove your improvements. And, as always, keeping the records for five or seven years past the sale is an even better bet.
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