Extensions to the Wealth Tax Neutrality Framework

Battle Count: 50

The paper is primarily a tax policy and portfolio theory paper rather than a trading strategy paper. However, it has moderate relevance to quantitative trading through: (1) understanding tax-induced portfolio distortions that affect equilibrium asset prices and Sharpe ratios; (2) the inelastic markets channel (Gabaix-Koijen multiplier) which is directly relevant to market impact modeling and execution; (3) the Heston/Markov diffusion framework for stochastic volatility; (4) implications for asset allocation in taxed jurisdictions; (5) the price impact of large-scale tax-driven flows. The paper does not propose trading strategies or use ML-based prediction models. Its primary contribution is to the theoretical understanding of how taxation interacts with portfolio choice and market microstructure.

The mathematical framework is highly complex, involving: (1) HJB PDEs with stochastic volatility state variables; (2) exponential-affine solutions and Riccati equations; (3) multi-asset portfolio optimization with non-uniform tax assessment; (4) general equilibrium price impact modeling with demand multipliers; (5) progressive tax bracket structures with threshold effects; (6) migration decision models in (W, c_i) space. Implementing the full framework requires advanced stochastic calculus, PDE solving, and calibration to country-specific tax systems. The individual propositions are analytically tractable but the integrated framework (Section 8 synthesis) requires substantial computational infrastructure for numerical solutions.

The paper is primarily theoretical with analytical proofs. Calibrations use publicly available Norwegian tax parameters (Skatteetaten 2026) and published empirical estimates (Gabaix-Koijen multiplier, Calvet-Sodini elasticity). However, no code or data repository is provided. The mathematical derivations are self-contained and verifiable. Key empirical inputs (Norwegian emigration data from Civita, Ministry of Finance) are referenced but not reproduced. The framework is reproducible in principle given the stated parameters, but full replication requires access to Norwegian registry data.