Should return metrics be calculated on pre or post tax cash flow?

[David Jiang]

I'm putting together a Pro Forma from scratch for a potential commercial property I am thinking about buying. I want to calculate cash-on-cash return, NPV, and IRR. Should these calculations be done on pre or post tax cash flow? Which method results in a more meaningful returns metric?

As an extension to this question, should inflation in be included in any of these calculations? Thanks!