The historical-cost and prudence principles have guided accounting for financial investments and tangible fixed assets in many jurisdictions around the globe. This situation might change as a consequence of the increasing number of countries adopting International Financial Reporting Standards (IFRSs), which, to some extent, permit accounting on a fair-value basis. This paper attempts to restate the financial investments and tangible fixed assets of a sample of 14 Taiwanese insurance companies, applying fair value instead of historical-cost-based valuations by using data envelopment analysis (DEA). I find that the numbers on the face of the financial statements change considerably and observe that the magnitude of these changes varies between companies and classes of assets. The overall assessment of companies with regard to efficiency and profitability remains largely the same under both valuation bases.