I'm not sure that's what your chart shows, but whatever.
Originally Posted by Doove
Let me try and explain it to you using small words.
The line graph shows the capital gain tax receipts in each year as a percentage of GDP. The bar graph at the bottom is the capital gains tax rate in effect for that year.
The only time the line graph is above the 50 year average is when tax rates are either low, or just before they are sharply raised (i.e., people selling in anticipation of a rise).
The explanation for this is pretty simple. People only pay a capital gains tax when they sell an investment assets. When rates are high, they are less likely to sell because they can't earn as much value after they pay their taxes.
For example, suppose that you have owned an asset that you bought for $500 10 years ago which is now worth $1,000. That asset is appreciating 7.2%, so 10 years from now it will be worth $2,000.
If you sell that asset, you won't have $1,000 to reinvest because you have to pay taxes. If rates are 15%, you'll have about $925 after you pay a $75 tax on the $500 capital gain (i.e., the difference between the $1,000 its worth and the $500 you paid). If you reinvest the $925, you would have to get an 8.0% return to break even -- i.e. so that the new asset would be worth $1,000 in 10 years.
But if tax rates go up to 35%, your tax bill if you sell would increases to $175 and you would now need to earn 9.3% or more to break even. That 1.3% additional return might not seem like much, but it is. Over a 10 year horizon, that is about equal to the difference between an average return and a bad one in most asset classes. If you can only get the same 8.0%, your reinvested asset would only be worth $1,784 - $224 less.
Is it any wonder that capital gain tax receipts fall when tax rates rise?