The current IRS policy is that filing compliance constitutes the last 6 years tax returns. Why is that? This is an administrative directive by the IRS because they do not have the real-time capability to go back more than 6 years (the IRS only keeps your income documents in real-time for the last six years). The IRS reserves the right to ask for more than the past six years and they often do in two situations:
1. When you file an Offer in Compromise
2. When you have a business that is formed as a corporation or partnership
It is virtually impossible to file accurate returns for the last six years without some professional help. Make sure the professional assistance you obtain has the ability to gather the IRS records for the past six years to make the delinquent returns you file at least minimally processable.