If you ask me? A very large consumption tax would probably handle most of it, as well as some form of asset taxation (eg. on land and voting-rights shares, in terms of their equivalent rental value).
This would basically amount to a leveling function across society: people consuming less than the mean earn (much) more in UBI than they pay in sales taxes. Wealthier people who consume more than average would pay in more than they get out. With wealth being power-law distributed, the wealthy would end up paying a lot more.
Then you just tune the UBI value to achieve any desired balance of equality vs incentive to work, while adjusting the tax take to control inflation.
The megacorp wealth flows back to the shareholders, who eventually will want to spend it on something.