Atlanta ( CNN ) -- Last week we learned that Barack and Michelle Obama 's effective tax rate for 2011 was 20.5 % . They had adjusted gross income of $ 789,674 . We also learned that their tax rate was slightly lower than President Obama 's secretary , who had about $ 95,000 of income . Ours is supposed to be a progressive rate system , which means as income gets higher , so do tax rates . In a true progressive rate system , Obama would never pay a lower tax rate than his secretary . We also know that Mitt and Ann Romney have a projected effective tax rate of 15 % for 2011 . They have requested an extension so we do n't have their actual returns . Their household income was just shy of $ 21 million . In a true progressive tax system , the Romneys would never pay a lower tax rate than the Obamas . We do not have a progressive tax system . The notion of a progressive tax system is the lie that has been perpetuated far too long . First , not all income is taxed the same . While our income tax has always had progressive rates , for most of the 20th century a lower rate applied to certain nonwage income . That rate differential was increased dramatically as a result of the Bush tax cuts . Most of the Romneys ' income comes from stock ownership . Stock dividends and capital gains are generally not subject to our progressive rate system . Income from stock is taxed at a flat 15 % rate . Fewer than 1 in 5 Americans owns stock in a way that qualifies for the flat rate . Of that minority , very few benefit the way the Romneys do . An analysis of IRS statistics show that for households up to $ 200,000 , no more than about 5 % of their income is eligible for the flat 15 % rate . Those households combined represent well more than 90 % of American households . The Simpson-Bowles commission included a proposal that all income should be taxed the same . While some would say that is a radical step , it is precisely what we did in 1986 . Second , not all deductions are treated the same . Two-thirds of all taxpayers do not itemize their deductions but take the standard deduction . So , as a result , most Americans do not even benefit from the myriad of special interest group deductions found in our tax code . In addition , under a progressive tax system , the value of a deduction depends upon what rate your last dollar is taxed . That is referred to as your marginal tax rate . The more income you have , the higher your marginal tax rate and the greater the value of the deduction . For example , if your marginal tax rate is 35 % , then for every dollar you spend , you save 35 cents . If your marginal tax rate is 15 % , then for every dollar you spend , you save only 15 cents . That explains why those in higher income brackets seek out tax deductions as a way to save money on their taxes . Third , all of this is supposed to be a secret . The only reason we have the information is because taxpayers voluntarily disclosed it -- either because they are presidential candidates or concerned citizens such as investor Warren Buffett . The IRS statistics do a great job of masking this information because the real problem lies within the top 1 % of taxpayers , and the data are not presented in a way that isolates that group . Congress decides to enact a tax law , and the president signs the bill . While presidents voluntarily release their tax returns , members of Congress do not . The first step toward real tax reform would be for every member of Congress to release his or her tax return . We can see which tax provisions benefit them , and we can compare their effective tax rates with our own . Achieving meaningful tax reform will require very few steps . First , tax all forms of income at the same rate . Second , repeal the progressive tax system and enact a flat tax . If a flat tax is good enough for Mitt and Ann Romney , it should be good enough for the rest of us . Most flat tax proponents , however , want a flat tax , but they want to exempt income from stock completely . That would mean Mitt and Ann Romney 's already low 15 % effective tax rate would be cut even further . That would be wrong-headed tax reform . Finally , most deductions should be eliminated . Most taxpayers do not itemize , so this change would only affect about one-third of taxpayers -- and their accountants and tax lawyers . Whenever Congress enacts a deduction , it creates winners and losers . That must stop . To be sure , every special interest group will oppose even the hint of this suggestion . But we outnumber them . I do n't think it 's fair that the richest Americans pay taxes at a lower rate than most taxpayers and neither should you . The opinions expressed in this commentary are solely those of Dorothy Brown .
Dorothy Brown : We live with the myth that we have a progressive tax system . In fact , she says , people like Mitt Romney , Barack Obama pay at lower rates than secretaries . She says the low flat rate on dividends and capital gains protects the wealthy . Brown : Getting rid of the progressive tax brackets is a step toward a fairer system .