The correction period begins on the date of the taxable expenditure and ends 90 days after a notice of deficiency for the additional tax is mailed. The period is extended for the time during which a deficiency cannot be assessed under Code section 6213(a) (relating to pending Tax Court and other proceedings), and for any other period the Service determines is reasonable and necessary for correction of the taxable expenditure. Additional information Correction period overview Correction during correction period Return to life cycle of a private foundation