Purpose An intractable effect of revenue and expense recognition based on tax regulation and accounting rules is unresolved and may be manageable only by reducing the value of deferred taxes. Therefore, in this study, the authors examined the relationship between the International Accounting Standard 12 (IAS 12) and deferred income taxes associated with tax and accounting rules. Design/methodology/approach The authors used a large sample of balanced data from 144 firms across 1992–2019. To mitigate the problem of superfluous results, the authors used the same number of firms and years for pre- and post-IAS 12 periods. The authors employed robust econometric estimations to establish the impact of IAS 12 on deferred tax. Findings The regression results show that deferred tax assets decreased significantly, whereas deferred tax liabilities increased significantly, in the post-IAS 12 period. These contrasting results imply that IAS 12 implementation has increased conservatism and prudence in financial reporting. However, the authors find that the increase in deferred tax assets post-IAS 12 is value destructive, suggesting that its implementation has unintended consequences. The results are robust to alternative measurements and econometric identification strategies. Originality/value While prior studies have explored topics such as deferred tax measurement and the impact of income and expense recognition, the authors specifically analyzed how IAS 12 affects deferred taxes and their effect on the market valuation. The authors find that certain accounting standards may not be relevant to the capital market.