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The IRS advises keeping tax returns for at least 3 years. If any of the returns contanes information that dealt with business or any forms that would show tax deferred amounts from IRAs (this would most likely be a Form 8606 and not before year 1998) then tohose should be kept as well for additional time preferably until those accounts have been distributed and are showing on the beneficiaries returns.
You must keep your records as long as they may be needed for the administration of any provision of the Internal Revenue Code. Generally, this means you must keep records that support items shown on your return until the period of limitations for that return runs out.
The period of limitations is the period of time in which you can amend your return to claim a credit or refund or the IRS can assess additional tax. Table 3 contains the periods of limitations that apply to income tax returns. Unless otherwise stated, the years refer to the period beginning after the return was filed. Returns filed before the due date are treated as being filed on the due date.
Table 3. Period of Limitations