The usual three-year statute of limitations on additional tax assessments applies in the following situation(s).

	a.	No return at all is filed.
	b.	An investment in a marketable security is worthless.
	c.	Taxpayer discovers an inadvertent overstatement of deductions equal to 30% of gross income.
	d.	Taxpayer inadvertently omits an amount of gross income equal to 30% of the gross income stated on the return.