have said - if their true wealth didn’t match their tax statements they would be audited. Seeing their tax records are made public each year it would be difficult to hide sources of income.
And as of now I bothered to do a quick search of the Biden income jump and found Forbes took look at Biden’s income. Link Posted above!
Cape’s link is wrongly suggesting dark money but apparently managed to get Biden’s sudden rise in income correct. Forbes lays it out as to why.