The calendar shows April 15th, and you haven’t even started on your federal tax return? Don’t fret. If you’re due a refund, April 15th isn’t much of a deadline at all. The Internal Revenue Service doesn’t like to talk about it, but penalties for filing late federal tax returns apply only to people who owe money. The penalty is a percentage of what you owe. If you owe nothing, 5 percent of nothing is …nothing. The IRS says about three-fourths of filers get refunds. Also, hang onto those supporting documents for your tax return. 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.