The reason I said "net carbon captured" was to avoid the "cobra effect" of people releasing carbon deliberately so they can capture it, or of people using fossi

The reason I said "net carbon captured" was to avoid the "cobra effect" of people releasing carbon deliberately so they can capture it, or of people using fossil fuel powered carbon capture that releases more than it captures. If they are paying high taxes on fossil fuels then it will quickly become unprofitable, so in that case it's not a serious problem. Assuming they are not later burnt, growing trees qualifies as carbon capture. I now realize the tax would have to be on all forms of CO2 emissions, not just fossil fuels, otherwise the captured carbon would be re-burned.