The Wealth Delta Tax: Scope Boundary — Questions Outside This Project
Wealth Delta Tax, research scope, research boundaries, methodological scope, open research questions, model limitations, deferred questions, legal questions, empirical questions, future research
Revision History
| Revision | Date | Details |
|---|---|---|
| 0.1 | 6 August 2026 | First draft. Twelve items from the consolidated open questions register formally acknowledged as outside project scope, with reasons. |
| 0.2 | 21 August 2026 | Full revision against the completed 30-item open questions register (0.0 §26). All items categorised and absorbed. Section taxonomy restructured to match register groupings. Internal bibliography extended. |
| 0.3 | 20 September 2026 | §2 removed: WFR closed all three formal modelling tasks (#1–3). §3 substantially reduced: INST and FAL have given #7 and #8 substantive theoretical treatment. Cross-references to LDW, FAL, and INST added throughout. |
1. Purpose
The consolidated open questions register (0.0 §26) lists every question the companion paper series raises but does not close. Those items are classified by group: confirmed literature gaps requiring formal modelling (26.1), Phase One empirical questions unanswerable before a live system (26.2), items assigned to MACRO as a Phase One successor (26.3), Governing Council calibration parameters settled in kind but open in value (26.4), and jurisdiction-specific and institutional preconditions that are not design gaps (26.5).
This document records which items are outside this project’s scope and why, and flags which have subsequently received substantial treatment in later papers. The categorisation matters: different reasons for deferral carry different implications for what a reader or subsequent researcher should do with each item.
2. Comparative Political Economy and International Coordination
#7 — Causal framework validation. The three-mechanism account of wealth tax abolition derived in (POL §3) has not been independently validated using formal comparative political science methods. (INST §4) extends and applies this framework at length, developing the structural exclusion argument from the same three mechanisms. What the project lacks is independent empirical validation through formal comparative case-study methods; INST acknowledges this and assigns it to the external research programme in (INST §10, Cluster 4). (LR.A §4.1) confirms the original literature gap.
#8 — International competitive dynamic at the political level. How sustained competitive pressure from other jurisdictions transmits through domestic political institutions to produce outcomes was underdeveloped in the project when SCOPE was first written. (INST §8) now provides a substantive treatment of memetic diffusion dynamics and the four response options available to non-adopting states. Formal comparative political economy research remains outstanding; (INST §10) assigns it to external collaboration. (LR.A §4.2) confirms the gap.
#9 — Minimum-tax floor interaction. Whether a negative-tax year under the symmetric loss-refund mechanism constitutes a breach of an international minimum-tax floor obligation, and how multi-year averaging interacts with that floor, is a legal and treaty question no refund-based wealth tax has previously raised. No project paper has addressed this. Resolution requires the international legal and tax treaty community. (LR.A §4.3) confirms it as a literature gap.
3. Phase One Empirical Questions
Ten items cannot be resolved by further desk research. The conditions under which each can be answered only come into existence once a WDT is operating. PHASE1 specifies evaluation designs for items #4–6, #13–16; items #18, #29, and #30 are flagged as Phase One tasks in ENV, VAL.A, and POL respectively. (FAL) has since given several of these items precise falsification structure — particularly #4, #5, and #6 within H1 and H3, and #30 within H3’s bootstrapping vulnerability analysis — but they remain empirically open.
3.1 Compliance and Behavioural Questions
#4 — Cooperative compliance at ultra-high-net-worth level. How professional intermediaries mediate the compliance psychology of ultra-high-net-worth taxpayers under the cooperative architecture requires a live system. (PHASE1 §4.1) assigns this to Phase One cluster 1. (FAL H3) identifies cooperative compliance as the variable its institutional equilibrium hypothesis most depends on.
#5 — Cross-base migration externality magnitude. Whether the WDT population’s migration response falls within, above, or below the six-to-one Agrawal ratio cannot be determined without observational data from a live system. (BEHAV §9.2) assigns this to Phase One cluster 3. (FAL H1) incorporates migration as an endogenous variable in the taxpayer preference hypothesis.
#6 — Administrative-layer intervention effects on compliance psychology. The effectiveness of the taxpayer history record on compliance psychology requires live observation. (PHASE1 §4.5) assigns this to Phase One cluster 5.
#18 — SRR floor calibration under mild-overstatement equilibrium. If mild overstatement is the stable equilibrium (ENV §2), the SRR floor calibration needs to reflect the implied refund liability. The calibration correction depends on observing the equilibrium distribution. (ENV §2) assigns this to Phase One.
#29 — Monitoring instrument for population distribution of \(\alpha\). The mild-overstatement parameter \(\alpha\) (VAL.A §A.6) cannot be observed directly; it must be inferred from assessment data over time. (VAL.A §A.6) and (BEHAV.A §B) assign this to Phase One.
3.2 Institutional and Operational Questions
#13 — Valuation route adoption distribution and flexibility levy calibration. The proportions in which taxpayers elect Routes A through D, and the assessment window adoption rate under Route A, determine the flexibility levy calibration. (PHASE1 §4.4) assigns this to Phase One cluster 4.
#14 — OBR independence assessment as mandate-guardian. Whether the Office for Budget Responsibility can function as the WDT’s mandate-guardian without structural modification is answered only by operating the role. (PHASE1 §4.6) assigns this to Phase One cluster 6.
#15 — Corporate instrument transition conditions. The conditions under which the corporate delta levy matures to the point where CIT displacement becomes a live policy decision cannot be specified in advance. (PHASE1 §4.7) assigns this to Phase One cluster 7.
#16 — Housing price net effect. The net housing price effect of the WDT depends on the composition shift in demand it induces. The net direction is ambiguous; (LDW §4.2) distinguishes the rental and ownership markets and reaches an honest conclusion that the ownership market question cannot be settled at the design stage. (ENV §9.2.2) assigns this to Phase One.
3.3 Systemic Risk Question
#30 — Bootstrapping problem: Phase One vulnerability window. Whether the mitigation measures in (POL §6) are sufficient to hold the system through the Phase One vulnerability window is not verifiable by design analysis. (FAL H3 §5.5) characterises this as the hypothesis’s most acute falsification territory and specifies the two paths available. Phase One is both the test and the only available test.
4. Phase One Successor Tasks
These two items are assigned to MACRO, a paper that cannot be written until Phase One data is available. They are not outside the project’s scope in principle; they belong to a future project this project has explicitly named and scoped. (ENV.A) sets out what MACRO requires and what it is expected to resolve. (FAL H2d and H5) incorporate both items as open empirical inputs to the macroeconomic and automation-resilience hypotheses.
#11 — Consumption multiplier magnitude and net bias direction of RATES estimates. Quantifying the multiplier and resolving the net bias direction requires a calibrated general equilibrium model that cannot be calibrated without Phase One data. MACRO is the assigned paper.
#12 — Automation and tax-base migration under different automation trajectories. The sensitivity of RATES estimates to automation scenarios is a modelling question requiring Phase One calibration data. Also assigned to MACRO.
5. Governing Council Calibration Parameters
These six items are settled in kind — the WDT specifies what each parameter does, what considerations govern its calibration, and what trade-offs bind — but open in value pending Phase One data. They are not scope boundary questions in the sense of (SCOPE §2)–(SCOPE §4): the project has done the design work; Phase One observation closes the value question.
#10 — SWF governance Phase One parameters. (GOV.B §A.3.4) specifies the DR floor size, constituency dissolution trigger values, and the DR Phase Two scale problem as parameters requiring Phase One data.
#17 — \(\tau_0\) × \(W_{min}\) joint surface. (SWEEPS §7.1) and SWEEPS.A identify this as the primary cross-dataset tension and the only item in this group resolvable without Phase One data, requiring a second-order sweep extension.
#19 — Liquidity threshold for thinly traded companies. (CORP §4.1) specifies the threshold’s function and the trade-offs that govern its calibration; the value is a Phase One parameter.
#20 — \(\tau_0\) exact calibration. (CORP.A §B.1) specifies the collection-security floor logic; the value is expected to require one to two cycles of Phase One observation.
#21 — \(\tau_h\) exact calibration. (CORP.A §B.2) specifies the deterrence-floor-to-\(\tau_m\) range and the joint calibration with CIT/dividend displacement; the value is expected to require three to five cycles.
#24 — Assessment window premium exact calibration. (VAL §8) and (RATES §4) specify the premium’s function; its calibration awaits Phase One adoption distribution data (see also #13).
6. Jurisdiction-Specific and Institutional Preconditions
These six items are not design gaps. The project has specified the relevant mechanisms in principle; resolution depends on legal analysis, diplomatic process, or institutional negotiation specific to a jurisdiction. JUR provides the reference jurisdiction architecture; it does not close these items.
#22 — \(\tau_f\) diplomatic rate-setting. The foreign-owner rate \(\tau_f\) is set by bilateral or multilateral agreement. CORP.A §F specifies the rate’s function and the negotiating frame; the rate itself is not a WDT design parameter.
#23 — Route D auction implementation details. The conduct rules for the Route D enforcement auction at implementation level are specified in principle in GOV.B §G. Jurisdiction-specific implementation requires legal drafting.
#25 — Derivatives valuation methodology for illiquid positions. The WDT’s valuation architecture covers the four primary routes (VAL) and the mathematical framework for self-balancing (VAL.A). Derivatives valuation methodology for illiquid positions in complex structured products is a specialist question for future methodology work in the VAL tradition.
#26 — HMRC data access agreement for microsimulation. (JUR §4.3) identifies the data access agreement required for microsimulation calibration. Whether HMRC grants access, under what conditions, and on what timeline is an institutional negotiation outside the project’s control.
#27 — Post-Brexit information exchange gaps. (JUR §4.3) identifies the loss of DAC and the treatment of EU-domiciled structures as information exchange gaps that post-Brexit arrangements have not closed. Closing them requires diplomatic process.
#28 — Constitutional and legal analysis of the Route D auction trigger. The constitutional status of the compelled-sale trigger, exit closure provisions, and the bridging facility’s interaction with deemed-disposal rules all require legal analysis the project cannot supply. (INST §5.3) develops the structural argument for why this analysis is a precondition for implementation under any specific jurisdiction’s constitutional framework, not a gap in the mechanism design itself.
7. What This Document Is Not Doing
Deferring these items is not a claim that they are unimportant. Several are consequential: the constitutional and legal analysis (#28) is a precondition for implementation in any specific jurisdiction; the bootstrapping vulnerability (#30) and the compliance and behavioural questions (#4–6) are the most consequential Phase One deliverables; the international treaty question (#9) has no project-internal resolution path.
The project states its remaining limits plainly rather than leaving forward references that never arrive.