If an investor pays $1,000 of capital, at the end of the year, he will have ($1,000 return of capital, $100 income and –$20 tax) $1,080.
If an investor puts in $1,000 of capital, by the end of the year, they will have ($1,000 return on investment, $100 income and a tax deduction of $20) resulting in a total of $1,080.