Taxable Income and Total Tax Liability are in thousands.

Ranges of Adjusted Gross Income

Item Under $$15,000$ $$15,000$ to under $$30,000$ $$30,000$ to under $$50,000$ $$50,000$ to under $$100,000$ $$100,000$ to under $$200,000$ $$200,000$ or more

Number of returns $39,269,40227,369,90927,138,63734,436,44920,908,8388,559,402$

Taxable income $ $6,938,229$ $ $192,881,768$ $ $604,264,808$ $ $1,753,557,416$ $ $2,304,350,171$ $ $3,864,997,623$

Total tax liability $ $777,332$ $ $14,769,011$ $ $50,115,871$ $ $186,008,777$ $ $317,634,367$ $ $906,217,543$

Average tax rate$*11\mathrm{.}20\%7\mathrm{.}66\%8\mathrm{.}29\%10\mathrm{.}61\%13\mathrm{.}78\%23\mathrm{.}45\%$

$*$The average tax rate is total tax liability divided by taxable income.

Required:

If the federal tax system was changed to a proportional tax rate structure with a tax rate of $17\%,$ calculate the amount of tax liability for $2021$ for all taxpayers.

What is the amount and nature of difference from actual tax liability specified in the above table?