The United States Securities and Exchange Commission (SEC) issued a Roadmap in 2008 regarding a change in the American accounting standards system. The Roadmap proposes a potential adoption from the United States Generally Accepted Accounting Principles (US GAAP) to the International Financial Reporting Standards (IFRS). The objective with the adoption is to enhance a one-set of accounting standards used in the world in order to increase comparability between public limited companies in different jurisdictions. With the adoption, the valuation of inventories for American companies will change, since the Last-In, First-Out (LIFO) method is allowed under US GAAP, but not under IFRS. A study from 2008 shows that approximately 36 per cent of American public limited companies is using LIFO. They would therefore be forced to use another inventory valuation method, such as First-In, First-Out (FIFO). The LIFO method is normally used by companies exposed to inflation and increases the cost of goods sold (COGS) and consequently lowers the net income and income tax provision. With the potential adoption, these companies would face large increases of income tax provisions, which would affect them severely.

This thesis is a review study with the objective to connect recent research with the SEC Roadmap in order to answer the following research questions: How will US companies that are using LIFO be affected by the inventory valuation change to FIFO, from an economic and accounting-based approach? What are the positive and negative aspects with a removal of LIFO regarding the IFRS adoption?

There is a clear benefit for the US companies using LIFO regarding the smaller income tax provisions. Opponents consider that LIFO will disappear with the US adoption to IFRS. At the same time, recent research considers or doubts that the LIFO method will not face its death with the adoption from US GAAP to IFRS. As a conclusion, the negative effect of removing LIFO as a consequence of this adoption, is the implementation time period, which is too optimistic. Even though, the credibility with a shift from LIFO to FIFO will grow stronger and create a more comparable business world.