Tariff Threats and Digital Tax Sovereignty

New UK tax residents who enter the tax system through Pay-As-You-Earn employment may assume that payroll withholding settles their full obligations, leaving overseas income, including rental receipts, business distributions, and foreign investment returns, undeclared for several years until HMRC detects the discrepancy through intelligence or international data exchange. This paper introduces the Disclosure Timing Gap: the structural interval between the moment a worldwide income obligation first arises for a new UK resident and the moment any administrative mechanism clearly signals that it exists. To close that gap, the paper proposes the Residency Tax Orientation Statement (RTOS), a brief yes-or-no orientation check embedded within HMRC's digital onboarding pathway, including GOV.UK One Login for new individual customers, directing users to existing guidance on overseas income obligations without creating liability, requiring asset disclosure, or triggering enforcement action. Drawing on policy design scholarship, behavioural tax compliance theory, and published HMRC administrative data, the paper develops an evaluation framework for testing whether such an intervention could reduce delayed disclosure and multi-year compliance enquiries. The analysis suggests that a low-cost, well-timed entry-stage prompt within existing digital infrastructure represents a proportionate and testable response to a foreseeable administrative design failure. This paper is a policy design analysis and does not provide individual tax advice; the RTOS proposal would require legal, operational, and data protection review before implementation.