Intro

Equity compensation is a powerful incentive—but the tax treatment of stock-based compensation (SBC) is anything but straightforward. And here’s where the real challenge begins: Global Mobility—the movement of employees across borders—adds a critical layer of complexity to equity compensation. As remote work and cross-border assignments increase, companies must ensure tax compliance aligns with where the services were actually performed.

When employees or contractors cross jurisdictions, there's often a fundamental mismatch between the timing of tax events and the location where services were performed. This directly impacts how countries attribute the “source” of income. And it becomes especially problematic when beneficial tax treatments are involved—like ISOs in the U.S., EMI or CSOP in the UK, ESS in Australia, Section 102 in Israel, SME programs in Portugal—the list goes on.

And mobility isn’t just an international issue—moving between U.S. states can also trigger major tax implications. Each U.S. state has its own rules for reporting, withholding, income sourcing, and residency—making even domestic mobility a tax compliance minefield. 

In fact, relocating prior to selling the underlying shares can cause a complete forfeiture of tax advantages. This risk is heightened by the possibility of double taxation across countries, especially when vesting is ongoing. In some cases, the mere act of moving across borders can trigger a taxable event—commonly referred to as an 'Exit Tax'—or create new reporting obligations. This doesn’t just impact employees—companies are also facing increased administrative burdens and a high risk of challenges such as misapplied withholding rules by payroll teams, reporting failures, penalties, audits, and more.

The recent 2025 Global Disputes Forecast by Baker McKenzie highlights global employee mobility as “the chief driver of tax dispute risk for 62% of respondents.”

A Smarter Two-Layered Solution from Slice‍

While most tools rely on static or fragmented data inputs, at Slice we address mobility complexity with the combined power of two integrated solutions:

1. A tailored, real-time data model fed by ongoing HRIS sync

2. A smart compliance engine powered by deep knowledge from compliance and tax experts

Together, our platform gives multinational companies the full picture and not just the sum of fragmented systems. Let’s take a closer look at how Slice is built to handle mobility.

Unifying Fragmented Data into a Tax-Ready System

‍In most companies, residency information is stored in payroll or immigration systems, equity data lives with legal or HR, and grant history is buried in spreadsheets. That fragmentation makes it easy to miss critical tax events, lose tax advantages, or trigger unexpected liabilities—for both the company and the stakeholder. As evidence, KPMG’s 2024 Global Mobility Benchmarking Survey found that about 54% of respondents identified 'data spread across multiple systems' as one of the biggest challenges in implementing global mobility analytics.

Slice doesn’t just show you what’s happening—we help you understand when and where it matters for taxation across jurisdictions.

For example, consider a UK employee who received a grant in the UK under the EMI tax treatment, begins their vesting period, relocates to Singapore, and then exercises their options while working remotely from Canada. Even if you identify this case, just figuring out the details would take hours of manual work. In cases like this, you need to assess tax scope across countries, manage potential loss of UK EMI benefits, handle reporting duties in the UK or Singapore, and still watch for possible tax perks in Canada. A single equity event turns into a cross-border compliance maze.

That’s where Slice comes in—providing accurate, up-to-date mobility data to help the company stop flying blind. With Slice’s powerful data and features, finance teams are empowered to handle complex calculations with confidence—whether it’s modeling scenarios, managing recharge agreements, or accounting for stock-based compensation. By eliminating guesswork from the calculation process, our platform ensures financial accuracy and audit readiness for every tax event.

This is made possible by the Slice platform’s unique data model, which integrates a variety of data points:

• Stakeholder data (residency history, nationality, employing entity, relationship with the company, address changes)
• Equity lifecycle data (tax treatment, grant dates, vesting schedules, exercises, etc.)
• Company-level data (cap table and share classes, valuations, plan details, and more)

Because all this data is intelligently structured in one place, Slice doesn’t just show you what’s happening—we help you understand when and where it matters for taxation across jurisdictions, based on the specific tax treatments in each location. ‍

The Compliance Engine: Making Tax Logic Actionable‍

When it comes to global mobility, evaluating the actual tax impact across jurisdictions is a time-consuming and high-stakes challenge for legal, tax, finance and payroll teams. As an indicator of how significant the impact can be — the recent 2025 Global Disputes Forecast by Baker McKenzie highlights global employee mobility as “the chief driver of tax dispute risk for 62% of respondents.”

In practice, global mobility raises complex questions around income attribution and tax event sourcing that go far beyond basic residency rules—even when the taxable event occurs in a single location. Layer onto that the application of bilateral tax treaties, each with its own tie-breaker tests, foreign tax credit mechanisms, and mutual agreement procedures, and the result is a highly intricate matrix of rules and administrative practices.

That’s why Slice’s Compliance Engine goes far beyond surface-level alerts. At its core is a robust and continuously updated knowledge base of international taxation—built by compliance professionals who understand the intricacies and logic of global equity compensation. The engine captures how each jurisdiction treats equity events and applies local rules to each stakeholder and grant.

Slice’s Compliance Engine runs behind the scenes—integrated into the platform’s key workflows—to:
• Flag mismatches between tax treatment and residency
• Detect soft spots such as missing treaty coverage or dual taxation risks
• Provide real-time insights into potential tax events, reporting obligations, and possible benefits or losses under new tax regimes.

This enables our platform to deliver a proactive, intelligent solution—built on jurisdiction-specific, event-based logic—that understands tax nuance, maps employee journeys, and transforms compliance risk into operational clarity with actionable outcomes. 

Whether you're managing assignees, remote employees, or globally mobile talent—whether you're expanding globally or simply staying ahead of audits—Slice’s Compliance Engine has you covered from grant to exit. By delivering structured insights tailored to each stakeholder’s tax residency, mobility footprint, and award lifecycle, the Compliance Engine empowers tax teams to focus on strategy, not reconciliation.

The result? Finance and tax teams can detect mobility cases earlier, reduce reliance on manual processes, and engage advisors only when formal consultation is truly necessary.

Don’t take our word for it though, schedule a demo today and see for yourself why the world's fastest-growing companies trust Slice to manage global equity compliance: https://www.sliceglobal.com/demo-page