Why "probably OK" is a risky cross-border tax strategy
Context and Challenge
The main challenge with cross-border tax compliance is that many positions survive unchallenged not because they are correct, but because they used to be difficult to detect. That is changing. HMRC now receives more data from more sources than ever before, and tax authorities worldwide are exchanging information, using more data and becoming more joined up. They are learning to use AI to discover non-compliance. Common symptoms include historic positions with tax, payroll, pension and social security gaps or errors.
Who Should Read This
UK employers, boards, CEOs, HR directors, finance directors, CFOs, internationally mobile executives, non-executive directors, founders, family offices, trustees and professional advisers dealing with cross-border tax, payroll, social security reporting obligations.
Core Finding and Summary
HMRC receives more data from more sources than ever before. Cross-border tax, payroll, social security and reporting positions that are not technically correct face rising detection risk. Review the full position across all relevant jurisdictions before HMRC and other tax authorities ask the first question. Correct errors proactively. Ensure the evidence file supports the position taken.
In practice: If a position is not correct and fully aligned across jurisdictions, the probability of detection is rising. Review cross-border positions at least every six months or when circumstances change. Tax authorities worldwide are exchanging information, using more data and becoming more joined up. They are learning to use AI to discover non-compliance more quickly and more effectively than before.
Main risk: Tax, penalties, interest, duplicated liabilities, lost planning options, governance failures and reputational damage.
Technical reference: HMRC's expanded data sources include CRS, FATCA, Making Tax Digital, employer real-time reporting and international exchange of information agreements.
Decision point
Is the current cross-border tax, payroll, social security and reporting position correct, aligned across all relevant jurisdictions and supported by sufficient evidence if challenged?
The Issue
What triggers the issue?
HMRC and overseas tax authorities now receive more data from more sources, increasing the probability that incomplete or incorrect positions will surface. They are learning to use AI to discover non-compliance more quickly and more effectively than ever before.
Why does it matter?
Non-compliance can lead to expensive tax bills, penalties, interest, duplicated liabilities, lost treaty relief, governance failures and reputational damage. The wider risks extend well beyond the original tax underpaid.
What decision is needed?
Determine whether the full cross-border position is technically correct, aligned across jurisdictions and evidenced. Correct weaknesses before HMRC and other authorities identify them.
Technical Analysis
1.The changing compliance landscape
A cross-border tax position is correct when it accurately reflects the law, treaties and obligations in every relevant jurisdiction. For many years, some tax, payroll, residence, social security and reporting risks survived because they were difficult to see. That is changing.
HMRC now receives information from UK banks, employers, pension providers, online platforms, overseas tax authorities and financial institutions. International exchange of information under the Common Reporting Standard and FATCA means that foreign accounts, investments and structures are more visible than they were. Making Tax Digital moves more taxpayers towards more frequent, structured digital reporting. Employer real-time information reporting provides HMRC with payroll data as it arises.
HMRC does not need a complete picture to identify risk. A foreign account, a UK directorship, a Companies House appointment, rental property, platform income, share plan reporting or an overseas payroll record may each be enough to generate the first question. Once that question is asked, the burden often shifts quickly to the taxpayer or employer to explain the position, produce the evidence and correct any weakness.
The practical issue is not whether HMRC has a complete picture. The issue is whether HMRC already has enough data to challenge the position taken. In a data-led compliance environment, "probably OK" is becoming a risky strategy. Tax authorities are also quickly learning to use AI to use all this data to discover non-compliance more quickly and effectively than ever before.
2.Cross-border alignment: why single-country review fails
Cross-border alignment is the process of ensuring that the tax, payroll, pensions, social security reporting treatment of an individual or employer is technically consistent and correctly coordinated across every relevant jurisdiction.
A cross-border tax position cannot only be assessed one country at a time. Residence matters, but it is only one part of the analysis. A person may be resident or employed in one country, working in another, paid from a third, taxed through a shadow payroll in a fourth, receiving equity from a parent company in a fifth and holding investments or property elsewhere. The correct answer cannot be reached by looking only at the country of residence.
A proper cross-border review should consider how the relevant jurisdictions interact. That includes where the person is tax resident, where employment is and where duties are physically performed, which country has primary taxing rights, whether a treaty applies and is properly evidenced, where payroll withholding is required, whether foreign tax credits are available, whether social security remains in the home country or shifts to another country, how equity awards should be sourced, taxed, and reported, and whether capital gains, exit tax, inheritance tax or permanent establishment issues arise.
This is where single-jurisdiction advice fails. The correct answer is often not the UK answer, the US answer or the French answer in isolation. It is the aligned answer across all relevant jurisdictions. A position that appears correct from one perspective may be incomplete or incorrect when viewed across the full picture.
3.Beyond income tax: the taxes most often overlooked
Overlooked taxes are tax obligations that sit outside the routine income tax return process and require separate, jurisdiction-specific analysis.
When individuals and businesses think about tax risk, they often focus on income tax or corporation tax. That can leave significant exposures unchecked.
Payroll and employment taxes are a major risk area. PAYE, wage withholding, employer social security, benefits reporting, expenses, equity reporting and gross-up tax policies can all create liabilities. For employers, these costs may fall on the business even where the underlying issue relates to an employee.
Social security can be particularly expensive. Unlike income tax, contributions may not always be creditable in another country. Employer contributions can be significant in some countries. Mistakes can also affect employee entitlements, pension rights, healthcare coverage and assignment costs.
Capital taxes are easy to overlook. A move between countries can affect the taxation of shares, carried interest, options, property, investment portfolios, trusts and business disposals. Timing can be critical. A disposal before or after a change in residence may produce a materially different outcome.
Estate, inheritance and gift taxes require separate analysis. Residence is not always the only connecting factor. Domicile, deemed domicile, situs of assets, citizenship, treaty coverage, trusts and succession planning may all be relevant.
VAT and indirect taxes are another frequent gap. Consultancy, online services, property, management charges and cross-border trading can all raise VAT or overseas indirect tax questions. A holistic review should look beyond the income tax return.
4.Timing: why delay is not neutral
Timing risk is the loss of corrective options, planning opportunities or penalty mitigation that occurs when a compliance weakness is identified too late.
Some tax problems can be corrected. Some can be mitigated. Some can only be explained. The timing of the review is critical.
Before an issue crystallises, there may be options. A taxpayer may be able to adjust travel patterns, correct payroll, obtain a certificate of coverage, restructure remuneration, amend contracts, align employer reporting, make a disclosure, file a claim, obtain treaty evidence or correct historic filings. A voluntary disclosure, properly prepared and supported, is generally a stronger position than waiting for HMRC or other tax authority to identify the issue first.
After an enquiry or audit is opened, those options may be narrower or disappear. The taxpayer or employer may be explaining a past position rather than planning a better future one. Records may be incomplete. Advisers may have changed. Employees may have left. Foreign filing deadlines may have passed. Claims for relief may be out of time.
A weak position does not usually become stronger with age. It becomes harder to evidence, harder to correct and more expensive to resolve. Delay can turn a manageable issue into a tax, penalty, governance and reputational problem.
5.Governance, reputation and stakeholder risk
Tax governance is the framework of controls, reporting, oversight and accountability that ensures cross-border tax positions are technically correct, properly evidenced and reviewed at an appropriate level within the organisation.
Tax compliance is now a governance issue as well as a stakeholder risk issue.
For employers, failures in payroll, employment tax, social security, VAT or employee compliance can raise questions for finance, HR, legal, reward, internal audit and the board. For regulated businesses, listed groups or professional services firms, the reputational consequences may be more serious than the tax itself. The timing of a failure could be devastating to an organisations looking to raise finance or shareholder value during an IPO process.
For senior executives and non-executive directors, personal tax issues can have governance consequences. A director who has taken an aggressive or poorly evidenced personal tax position may face questions about judgement, disclosure and credibility. A business that fails to manage mobile employee compliance may face employee relations issues, unexpected gross-up costs and internal control concerns.
For family offices and trustees, the question is whether the family's assets, structures, reporting obligations and succession planning have been reviewed across the relevant countries. A narrow annual tax return process may not be enough.
Tax risk is no longer simply a private matter between taxpayer and adviser. It sits within a broader framework of governance, reputation, regulatory expectation and stakeholder confidence.
Case Scenario
Senior Executive with Multi-Jurisdiction Exposure
Situation: A UK-resident executive holds a non-executive directorship in Germany, receives equity awards from a US parent company, and owns rental property in France. Annual personal tax returns are filed in the UK only. The employer operates UK payroll but has not considered overseas obligations.
Issue: Whether the executive's cross-border position is fully compliant when only one jurisdiction has been reviewed.
Analysis: The German directorship creates potential payroll and social security obligations in Germany. The US equity awards may require sourcing across the vesting period, with withholding and reporting obligations in the US (Federal and State). The French property may create French income tax and social charge obligations. No coordinated cross-border review has been conducted. Foreign tax credit claims have not been filed. Social security coverage has not been formally evidenced.
Outcome: A multi-jurisdiction review identified undeclared obligations in two countries, expired foreign tax credit claims and a material social security gap. Voluntary disclosure in both jurisdictions avoided penalties. The employer corrected payroll reporting and implemented tracking controls.
Lesson: A position that appears correct from one country's perspective may be incomplete or incorrect when viewed across all relevant jurisdictions. The cost of a coordinated review is typically a fraction of the cost of a multi-jurisdiction correction under pressure.
Fenton International's Advisory Position
Technical position?
Cross-border tax, payroll, social security and reporting positions must be technically correct and aligned across all relevant jurisdictions. Rising data availability means incorrect positions face increasing detection risk.
Professional judgement required?
Yes — the interaction between jurisdictions, treaties, payroll structures, equity sourcing, capital taxes and governance obligations requires experienced cross-border judgement.
Main risks:
Tax underpaid
penalties
interest
duplicated tax
lost treaty relief
social security gaps
expired claims
governance failures
reputational damage
employee relations issues
reputational risks
commercial impact
transaction risk.
Evidence needed:
Tax returns
payroll records
travel records
contracts
treaties
social security certificates
equity plan documentation
property records
Copies of policies and decisions
corporate filings
historic advice.
Recommended controls:
Cross-border diagnostic
multi-jurisdiction alignment review
evidence file preparation
voluntary disclosure where appropriate
tracking and monitoring systems
governance reporting
periodic re-review
Professional Judgement & Advisory Application
Professional judgement is required where the interaction between jurisdictions produces outcomes that cannot be determined by reference to a single country's rules alone. This includes treaty conflict resolution, equity and other income sourcing across vesting periods, pension alignment, social security allocation, the interaction of capital taxes with residence changes, and the assessment of permanent establishment risk. The correct position is often the aligned position across all relevant jurisdictions — not the position that appears correct from any single perspective.
Fenton International's judgement and recommendation: review the full cross-border position before HMRC or any other tax authority identifies the issue. Assess technical correctness across all relevant jurisdictions, align the treatment, ensure the evidence file supports the position taken and correct errors proactively. Delay is not neutral.
Frequently Asked Questions
Does HMRC share information with overseas tax authorities?
Yes. HMRC participates in international exchange of information frameworks including the Common Reporting Standard and FATCA. This means that foreign bank accounts, investment income, employment records and other financial data held overseas may be reported to HMRC automatically. Similarly, UK data may be shared with overseas tax authorities. The scope and frequency of these exchanges continue to expand.
Can a cross-border tax position be corrected after HMRC opens an enquiry?
It may be possible to correct errors during an enquiry, but the options are typically narrower than if the correction had been made voluntarily. Penalty mitigation is generally more favourable for voluntary disclosures. Filing deadlines for foreign tax credits or treaty relief claims may have passed. The taxpayer is explaining a past position rather than planning a better one.
What taxes are most commonly overlooked in cross-border situations?
Social security contributions, employer payroll obligations in host countries, capital gains tax on residence changes, pension tax, inheritance and estate tax exposure, VAT on cross-border services and equity award sourcing across jurisdictions are among the most frequently missed. The common feature is that they sit outside the routine income tax return process and require separate analysis.
Who should commission a cross-border compliance review?
Internationally mobile individuals, senior executives with multi-country roles, non-executive directors with overseas appointments, employers with mobile or remote workers, family offices managing cross-border assets and trustees with international structures should all consider a periodic cross-border review. The question is whether all relevant taxes, jurisdictions and obligations have been considered together.
How Fenton International Can Help?
Fenton International helps internationally mobile individuals, executives, directors, employers and family offices review their cross-border tax, payroll, social security and reporting positions before they become compliance issues.
Multi-jurisdiction alignment reviews
Payroll, social security and reporting compliance
Voluntary disclosure and corrective action
Governance and evidence file preparation
Discuss this issue: Contact Fenton International for a cross-border director tax and compliance review.
Author
Mark Abbs, CEO, Fenton International
Fellow of the Association of Taxation Technicians (FATT)
Enrolled Agent of the IRS (EA)
Global Mobility Specialist – Talent Management (GMS-T)
Accredited Expert Witness (MAE)
32+ years' experience in international tax, cross-border employment tax and global mobility
Advises CFOs, HRDs, and Chairs on cross-border tax governance
Head of Advisory at Global Tax Network
Former Tax Partner, Head of International and Senior Leadership Team at Blick Rothenberg and Senior Tax Adviser in the Big 4.
Key terms: cross-border tax compliance, HMRC detection, international tax review, payroll risk, social security, exchange of information, CRS, FATCA, governance, voluntary disclosure, permanent establishment, capital gains tax, estate tax, cross-border alignment.
Scope note: This Insight addresses the general principle that cross-border tax positions face rising detection risk and should be reviewed holistically. It does not provide jurisdiction-specific technical guidance on any single country's rules. Professional advice should be taken for specific circumstances.
Jurisdiction: UK with multi-jurisdictional application | Last reviewed: June 2026 | Next review due: December 2026 | Insight type: Authority Piece
© 2026 Fenton International. All rights reserved.
This article is general information and not legal or tax advice. Professional advice should be taken for specific circumstances.
