This should be combined with my even more radical plan for fixing some irregularities in the year-by-year accounting system for income tax (notably, the fact that progressive taxation punishes you more for earning nothing for nine years and then $1m the tenth year, than for earning $100k steadily each year):
Annually, you calculate how much income you've earned over your entire life (and of course subtract any deductions you've become entitled to over your entire life). Then you look that up in a progressive (i.e. convex) tax function which tells you how much tax you owe for your entire life. Subtract the amount of tax you've already paid with all prior years' returns, and pay the difference.
Annually, you calculate how much income you've earned over your entire life (and of course subtract any deductions you've become entitled to over your entire life). Then you look that up in a progressive (i.e. convex) tax function which tells you how much tax you owe for your entire life. Subtract the amount of tax you've already paid with all prior years' returns, and pay the difference.