It would be helpful to give an example of what aspect of IAS 12 you’re interested in.  Depending on what jurisdiction you’re dealing with, one primary difference between many local GAAPs and IFRS on income tax accounting is around deferred tax accounting dealing with the temporary differences between the carrying balances with book and tax.  Another major part of IAS 12 is its many required disclosures.  Lastly, a significant part of the work around IAS 12 in practice is the reconciliation between the statutory tax rate and the effective rate, and the considerable rules of reporting that reconciliation (frequently called the proof of tax), and how things like currency fluctuations and tax rate change effects hitting deferred tax assets and liabilities are accounting for.