Keep copies of your returns forever. They can help when you apply for a mortgage or disability insurance or need the value of your assets. To save space, you can scan the returns and keep a digital archive.
Also save your canceled checks, receipts for home purchase costs, home improvements, and statements for credit-card and bank accounts, your home mortgage, stocks and mutual funds.
The IRS could audit you for up to three years, so keep those documents for at least that long.