Starting in 1964, the Standard Deduction became a fixed amount, prior to that it was a percentage subject to a cap. I was trained to use the Standard Deduction as a fixed amount (I was actually trained to use the "Zero Bracket Amount", which was only in effect in the late 1970s, then the system reverted back to Separate Standard Deduction and Personal Deductions).
I revised my thread when I found the reference I used as to the pre-1964 method of using the Standard Deduction AFTER I did my calculations. By the time I typed in the changes and was about to change the Paragraph to reflect the pre-1964 method, the one hour edit period has expired, so I left it go.
I had also by then found the Personal Exemption for the 1950s were $600 for someone filing as single, $1200 for a couple (Even if only one was working, which was the norm in the 1950s) AND $600 for each dependent. Thus the error I did as to the Standard Deduction was more then off set by the error of NOT including the Personal Deduction for the 1950s. If you had the 2.4 children that was the average in the 1950s, Total Deduction of $2400 (Married couple, Two Children). If you earned $4000, and was married with two children, your TAXABLE income was only $1600 LESS the Standard Deduction. 20% of $1600 is only $320 or 8% of $4000. Remember this is NOT including the Standard deduction which as you pointed out was NOT $500, but a percentage subject to a cap. Given the Standard deduction most people paid about 2% of their income as Income Taxes (Remember $4000 was median Income for most of the 1950s).
Personal Deductions:
http://www.taxpolicycenter.org/taxfacts/displayafact.cfm?Docid=543Furthermore the Standard Deduction was to be used when someone's Deductions (Other then the personal Deductions) did not exceed the Standard Deduction (This included things like interest on Credit Cards, car loans, student loan in the 1950s, the deduction for such interest was eliminated in the early 1980s under Reagan's rewrite of the Tax Code).
The law eliminating such interest from being deductible came around do to the fact by the 1980s most people were opting to NOT to use the Standard Deduction for the interests they were paying on car loans, credit Cards and other debts when combined with other deductions they could take exceeded the Standard Deduction. Reagan's solution was to raise the Standard Deduction AND eliminate the right to take such interest as a deduction (He did preserve the deduction for home mortgages but that was all).
Anyway, my point was most people did NOT earn more then $4000 in 1950, and a bare majority did by 1960. Given the nature of the Deductions permitted at that time, including the Standard Deduction AND the Personal Deduction, most such people were paying less then 2% on their income. Many were paying Zero.
The Minimum wage worker, if he did NOT take his personal exemption would have been paying 18%, but with the personal exemption of $600 for one person, $1200 for a couple, and $600 for each additional dependent, the rate would have been way zero (and if he was single living alone, $1500 less the $600 personal deduction is only $900, 20% of $900 is only $180 which is only 12% of $1500). This would be reduced by the Standard Deduction, but as you pointed out, it was a percentage subject to a cap and as such I am not doing the calculations (the IRS started to issue tables to reflect the Standard Deductions as part of the Income tax due, thus it would be more 18% then 20% on the amount left over AFTER the personal exemptions were taken).
Sorry, for the error, but the bigger error was me not finding the Personal Exemptions amounts till AFTER the period to edit my thread had expired.