What are the economic consequences of discounting deferred tax liability? I was wondering why the IAS prohibits companies from discounting their deferred tax items?

Are there any particular economic reasons for implementing such prohibition?

Thank you!
The answer is in the text of IAS 12, and basically amounts to "it's unreasonable to require it, and if we allow firms discretion in doing it, they will only do it when it's in their favor":


  The reliable determination of deferred tax assets and liabilities on a discounted basis requires detailed scheduling of the timing of the reversal of each temporary difference. In many cases such scheduling is impracticable or highly complex. Therefore, it is inappropriate to require discounting of deferred tax assets and liabilities. To permit, but not to require, discounting would result in deferred tax assets and liabilities which would not be comparable between entities. Therefore, this Standard does not require or permit the discounting of deferred tax assets and liabilities.