The transition to accrual accounting in the public sector began in practice in the 1990s. This move was made to prove the usefulness of accrual accounting in the public sector through scientific studies and practical experience. It has been observed that the most appropriate basis that can be used in public sector accounting is the full accrual basis or the modified accrual basis. However, despite the developments of the last two decades in the field of public sector accounting and financial reporting in the world, the modified cash accounting basis is still used in Iran and even the reforms in the country's budgeting system have not changed this situation. In this article, while examining the accrual and cash system and the obstacles to the transition to the accrual accounting system, the existing conditions in the government system of Iran are described and also the factors of non-implementation of the accrual basis are discussed. Finally, based on the relevant content, the adequacy of cash and accrual accounting systems in Iran will be evaluated.