Excerpt from SSRN here: A withholding based system will not be trapped in the tar pit of formation and implementation in the development of a new international tax regime, thereafter mired in 
the lack of institutional knowledge and capacity of resources for audit and MAP. A withholding based system offers a contrasted simplicity in relation to its implementation, including: (a) better procedural certainty for taxpayer and tax authority based upon current withholding regimes for services, (b) better revenue estimation for tax authorities, (c) less complex and expensive audits by tax authorities of taxpayers, (d) better tax risk management for taxpayers, (e) an established procedural system for relief of double taxation, and finally, (f) less cause for requiring MAP. Among proposals most likely to congeal into a uniform approach by March 2020, a withholding based system already has numerous adherents representing various economic strata. Read the complete Excerpt from SSRN here
Thus, rather than running away from a withholding based system into a ‘brave new world’, the OECD should embrace it and shape its current contours of definitional income and source issues and range of rates. Thereafter, the respective OECD and UN committees may leverage economic theory and regulatory impact analyses, as was done in 1923, to modulate the withholding based system via the inclusive process of the OECD and UN MTCs while working within the context of the ALP bedrock of the OECD and UN TPGs to address Article 7 and Article 9 allocation issues resulting from intangible-based residual. Read the complete Excerpt from SSRN here
William Byrnes' Tax, Wealth, and Risk Intelligence 