[Principled]

By your logic income tax would be a cost if there is a profit but NOT a cost if there is none.

If you don't pay income tax, is it a cost?

Beyond that li'l gem, there are costs that business pays even if their income tax liability is zero.

[justshutupandtakeit]

I speak only of the actual income tax itself not the costs of complying with the law which are not removed by lack of profits. So you can easily be in a situation where you pay no actual tax but pay thousands of dollars in costs.