Tax allowable depreciation

**Edit: I have found the answer in your free lectures so I understand it now, thank you! Though it seems like I cannot delete the topic so I will just leave it be**

“It can be assumed that the amount of tax-allowable depreciation is the same as the investment needed to maintain the companies’ operations.”

Can I say that when computing cash flow, I deduct TAD for tax allowance, but doesn’t add it back because it is being net-off with the TAD added back?

Thanks in advance!
Really appreciate it because I am weak when it comes to things related to tax and depreciation.