Gather all of the necessary tax documentation to file your taxes. Check to see if you have your W-2s, 1099s and other tax forms required to properly file your previous year's taxes. If you are missing any information, request duplicates from the issuing institution.
Obtain tax forms for the tax years you missed. For federal taxes, visit the Internal Revenue Service website and download the tax form for the years you need. If you have to file state taxes, visit the Department of Taxation and Finance for your state and download the necessary tax forms. If your state does not have the prior tax forms online, call and request that the forms be mailed to you.
Download the instructions for each tax year. As tax laws change, it's important to download the appropriate instructions for the correct tax year. What was perfectly acceptable one year may not be in the following year. Do not run the risk of exacerbating the late filing by filing it incorrectly.
Purchase tax preparation software for the prior tax years. Tax preparation software programs such as TaxCut and TurboTax allow late tax filers to purchase software going back as many as 5 years. If your tax filing needs predate the software, your best option is to visit the IRS website for the necessary forms and file paper forms.
Access an online service that specializes in filing taxes for previous years. Companies like PriorTax specialize in helping taxpayers who have not filed taxes from previous years. This type of service is only recommended if you are comfortable conducting business online exclusively. All PriorTax transactions are handled via email and online chat.
Contact an accountant. If you don't feel comfortable using an online service and prefer face-to-face interaction, make an appointment with an accountant to help you file your taxes from previous years. When you make the appointment, make sure to forewarn the accountant, and let her know which years you're looking to file.