Companies’ added value, even due to the expansion of the knowledge economy, is increasingly immaterial, and so is their taxable base: hence the importance of know-how, in spite of its ambiguous nature, to be tackled with an interdisciplinary accounting, financial and fiscal approach. Due to their immaterial nature, intangibles such as know-how are frequently negotiated within multinational groups, so becoming sensible to transfer pricing issues, which also depend on complex international accounting standards, with manifold corporate governance implications. OECD guidelines address the intricate problem trying to adapt standard transfer pricing methods to specific circumstances, but uncontrolled comparisons remain an uphill task, even if international accounting principles and market best practices may provide some useful hints for appraisal. To the extent that intangibles are unique, they cannot paradoxically be universal, so challenging arm’s length comparisons. Fair value market valuations, based also on critical accounting, consequently represent an uneasy and slippery benchmark. The optimal target is to disarticulate, on both economic and accounting terms, the value chain that rotates around know-how, attributing its belonging pieces to single taxpayers, so identifying a fair taxable base within each country, remembering that know-how is the engine behind growth ... and taxes.