Benefits from American IRA and 401(k) accounts - excel file

This Excel spreadsheet calculates the net benefit of American IRA and 401(k) accounts (vs normally taxed), and deconstructs the net into independent benefit-factors. Different sheets show how this understanding is used for various decisions. Common claims are proven false (eg. 'Profits are only tax-deferred and taxed at full rates on withdrawal', and 'Contribute to get the tax refund/reduction', and 'Your benefit depends on whether you contribute before-tax or after-tax dollars'.)