The Washington Post has this article about the primary season matching funds that Jill Stein has received this year. She has received $456,035. The article does not mention that no taxpayer is forced to pay into the public funding program. Instead, the form 1040 asks taxpayers if they wish to have $5 go to the fund. Most taxpayers say “no.”
The article does say that the fund is financed by voluntary tax checkoffs, and mentions the amount of people designating the $3 toward the fund has decreased.
Money quote: “Taxpayers have also expressed less interest in contributing to the public fund — with less than 6 percent checking the box in 2015, down from a high of about 29 percent in 1980.”
Now that few presidential candidates seek public funding, there probably is a lot less need for as many taxpayers to check the box. Less money is coming into the public fund, but a lot less is going out, too.
No particular taxpayer pays for these funds. All of us do, or, rather, the government borrows the money and we all pay the interest. The number of folks checking off just determines the size of the fund.