For the tax year 2020, Squash reported gross income of $300,000 on his timely filed Federal income tax return.

a.	Presuming that the general rule applies, on what date does the statute of limitations on assessments expire?
b.	Suppose that Squash inadvertently omitted gross income of $76,000. On what date does the statute of limitations on assessments expire?
c.	Suppose the omission was deliberate, not inadvertent. When does the statute of limitations on assessments expire?
d.	What if Squash never filed his 2020 tax return. When does the statute of limitations expire?