Feb 12th 2017, 3:16:19
Yes, the line expense item is called corruption:
E.G.
Expense Breakdown
Expenses $19,345
Military $12,219
Spies $939
Troops $143
Jets $0
Turrets $10,960
Tanks $177
Alliance/GDI $1226
Land $5900
Corruption $0
The corruption is 0.1% of each dollar over $2b per turn. Strictly speaking, your tax revenue doesn't decrease, its your expenses increasing. And like Marshal sort of said, that corruption expense can completely offset your tax revenues if it gets high enough. With $3b cash on hand, corruption = 0.001*($3b - $2b)= $1m per turn expense.
It would generally be better to spend the extra billion or two and buy jets to quad tap Kingme.