Prim-Lex Nine-Dimensional Framework for Global Tax–Climate Governance Coordination ——From Base Erosion to Climate Responsibility Tax: A Theoretical, Measurement, and Policy Framework (Version 2.0)

Global tax governance is undergoing a structural transformation, expanding from traditional issues of base erosion, profit shifting, and tax competition toward interconnected governance challenges that encompass carbon pricing, climate finance, border carbon adjustments, digital economy taxation, and international tax cooperation. As of 2026, direct carbon pricing policies cover slightly more than 29% of global greenhouse gas emissions, generating over USD 107 billion in public revenue in 2025—a more than threefold increase from less than USD 30 billion in 2016. The global average direct carbon price stands at nearly USD 21 per tonne of CO₂ equivalent, double the level of a decade ago. Concurrently, the OECD global minimum tax regime is advancing into further implementation and coordination phases, and the United Nations Framework Convention on International Tax Cooperation entered its fifth substantive negotiating session in August 2026. Global tax and climate governance are forming an increasingly complex institutional network.

This paper proposes the "Prim-Lex Nine-Dimensional Framework" as a cross‑scale, quantifiable, and testable analytical framework for assessing the coherence of global tax–climate governance. The framework partitions the global governance system into eight diagnostic dimensions and one directional dimension: Prim‑Unity·Prim‑Fire, Two Principles·Yin‑Yang, Three Realms·GC⁴A, Four Phenomena·Four Colors, Five Elements·Five Models, Six Directions·Six Dimensions, Seven Luminaires·Seven Rhythms, Eight Trigrams·Eight Information, and Prim‑Nexus·Guidance. The first eight dimensions describe the resource, institutional, spatial, temporal, and informational coordination states of the system; the ninth dimension specifies policy objectives, ethical constraints, and decision‑making direction.

The theoretical innovation of this paper does not assume that all governance variables naturally possess "phase" properties. Rather, it proposes that for policy, market, fiscal, and climate variables that can form stable time series, it is possible to map them into comparable dynamic state variables through standardisation, analytical signal transformation, Hilbert transform, cross‑spectral analysis, wavelet coherence, phase‑locking value (PLV), and Kuramoto‑type synchronisation indicators. On this basis, this paper defines a Global Tax–Climate Governance Coherence Index (GTCI) and proposes that the phase critical value should be estimated from data rather than presupposed as a universal empirical regularity of 45°.

As a demonstrative application, this paper draws on publicly available data from the World Bank, OECD, IMF, United Nations, European Commission, and WTO to conduct a structured diagnosis of global carbon pricing, the global minimum tax, the BEPS Multilateral Convention, CBAM, and international tax cooperation processes for 2025–2026. The results indicate that current global tax–climate governance indeed exhibits significant institutional heterogeneity, spatial imbalance, temporal scale mismatch, and information fragmentation. However, this paper frames these results as preliminary diagnostics and a framework demonstration rather than as fully econometrically identified causal conclusions.

Building on this foundation, this paper further proposes the "Climate Responsibility Tax" (CRT) as a policy design concept. The CRT does not advocate for a single global tax but proposes a coordination framework comprising carbon pricing, border carbon adjustments, climate finance, revenue redistribution, information transparency, and long‑term price pathways. This paper suggests that key parameters such as the global carbon price trajectory, revenue transfer ratios, and policy cycles should be treated as policy scenario variables and estimated through joint optimisation of welfare, abatement, fiscal, and distributional effects, rather than pre‑specifying any single tax rate or revenue share as uniquely optimal.

This paper thereby advances Prim‑Lex Theory from "theoretical diagnosis" to a "testable governance framework." Its core contribution is not to claim to have found definitive answers for global tax governance, but to propose a theoretical language that can be further datafied, econometrically analysed, compared, and falsified, and to provide a research pathway for the institutional transition from base erosion governance to climate responsibility governance.