Lost or missing documents can turn tax season into a giant headache, but they don't have to stall you for long. Here are some five common tax necessities that might go missing — and what a tax pro says you can do if they give you the slip.

Lost: Your W-2

Go to HR or your payroll department. A W-2 reports how much your employer paid you during the tax year and how much tax it withheld on your behalf. Generally, employers have to provide W-2s to employees by Jan. 31. If yours is lost or never showed up, simply ask your employer for another one. Check your old e-mails, too — many companies offer electronic access to company documents.

Lost: Old tax returns

Get a tax transcript from the IRS. This lets you see most line items from your federal tax returns for the current tax year and for returns processed during the prior three years. Tax transcripts are free, but note: they aren't the same as a photocopy of your tax return. If that's what you are after, you will probably need to fill out IRS Form 4506 instead (and there is a fee).

Lost: A 1099

Log in to your investment account. The 1099 is a record that some entity or person (not your employer) gave or paid you money. The most popular ones — the 1099-DIV, 1099-B and 1099-R — report dividends, capital gains and other income from investments or retirement accounts. If you have lost one of those, you can probably get another in the tax-documents section of your investment account's website.

Lost: Your 1098

Log on to your bank account.

A 1098 shows how much interest you paid on a mortgage during the year — interest that could score you a tax deduction. Your mortgage lender likely provides access to this and other tax documents (such as your property tax payments) online.

You can also look at your year-end mortgage statement to recreate the information.

Lost: Enough time to do your taxes

Get an extension. If the wait for missing forms will go beyond April 15, you can use IRS Form 4868 to get an extension. But beware: An extension gives you more time to file your tax forms — it doesn't give you more time to pay your taxes. You will still need to estimate how much you owe and pay the amount by April 15.