Tax base of liabilities

[Submariner]

The book says that for a customer advance, the tax base is equal to the carrying value minus any ammounts that WON’T be taxed in the future. On the other hand, for warranty liability the tax base is equal to the carrying value minus the ammount that WILL be deductable in the future.
Is there any reason for the difference and if so, does this apply to other expenses not covered by the examples in the book?

 

[S2000magician]

In the case of customer advances, you expect future revenues; in the case of warranty liability, you expect future expenses.

 

[Marwen Eltaief]

Customer advance and warranty are both liabilities and their tax bases are thier carrying amounts minus amounts that will not be taxed in the future… WON’T be taxed and deductible are the same thing