Selecting and managing a cross-border tax and global mobility adviser.

Fenton International supports procurement teams, corporate buyers, HR leaders, finance directors, and legal functions evaluating, appointing, or managing specialist advisers for cross-border tax, global mobility, payroll, social security, and international workforce matters. The firm helps buying teams define scope, evaluate capability, and ensure the selected provider delivers defensible, senior-led advisory — not just process.

How Fenton Private Office supports you

Fenton Private Office supports buyers and procurement teams through the Employer Advisory Office. Fenton can act as a specialist advisory provider or as a second opinion alongside an existing panel adviser.

The three service levels: Case Review, Lead Counsel and Discovery — provide flexibility for procurement teams to engage Fenton at the appropriate depth for each requirement, from senior review of existing advisory positions through to full-service delivery or structured compliance review.

Our team has held multiple senior leadership and board-level positions in HR, reward, and governance, managing budgets, delivering and setting strategy, and boardroom scrutiny. We bring the practical judgement of people who have owned the problem — not only advised on it.

When this needs immediate attention

→ An urgent cross-border tax or mobility matter has arisen and no suitable adviser is on the approved supplier list
Q: What may be at stake? The business may appoint reactively — selecting on availability rather than capability, expertise, or value for money.
Q: Why early action matters? A structured but accelerated evaluation protects the appointment decision and ensures the right specification is met.

→ The incumbent adviser is underperforming, providing narrow scope, or lacking senior involvement
Q: What may be at stake? Stakeholders — HR, finance, tax, board, employees, directors — may be receiving advice that is incomplete, inconsistent, or not defensible.
Q: Why early action matters? Benchmarking the current provider against a clear specification identifies whether the issue is scope, capability, or relationship.

→An internal audit finding, HMRC enquiry, or compliance failure has exposed gaps in existing advisory arrangements
Q: What may be at stake? The business needs to demonstrate that it has a credible plan to appoint or replace an adviser — and that the appointment process is defensible.
Q: Why early action matters? A well-specified and documented supplier evaluation gives the audit committee and stakeholders a governance-grade response.

→ Multiple providers — tax, immigration, relocation, payroll — are delivering fragmented advice with no single owner
Q: What may be at stake? Procurement may be managing several contracts but no one holds the integrated advisory position.
Q: Why early action matters? Evaluating whether a coordination layer is needed — and what to specify — prevents continued fragmentation.

→ A budget cycle, panel review, or contract renewal is approaching
Q: What may be at stake? The opportunity to respecify, benchmark, or retender may be time-limited.
Q: Why early action matters? Starting the evaluation early ensures sufficient time for proper specification, stakeholder consultation, and due diligence.

→ Senior stakeholders are asking why the business uses a large firm rather than a specialist — or vice versa
Q: What may be at stake? Procurement needs an evidence-based rationale for the appointment decision, proportionate to risk and complexity.
Q: Why early action matters? A documented evaluation against defined criteria provides a defensible answer regardless of which provider type is selected.

Other issues we can help with

→ The supplier evaluation, due diligence, and scope definition issues relevant to appointing a cross-border tax and global mobility adviser.

→ Defining the specification and scope of cross-border tax and global mobility advisory services before going to market

→ Evaluating specialist advisory providers against capability, expertise, senior involvement, and value for money

→ Distinguishing between advisory, compliance, payroll processing, immigration and relocation administration providers

→ Conducting proportionate due diligence on a specialist or boutique advisory firm

→ Managing an incumbent provider relationship where performance, scope, or quality is under review

→ Ensuring the selected supplier can coordinate with existing providers, including immigration, employment law, payroll and relocation, without creating gaps or duplication

Our team has held multiple senior leadership and board-level positions in HR, reward, and governance, managing budgets, delivering and setting strategy, and boardroom scrutiny. We bring the practical judgement of people who have owned the problem.

Your issue → Fenton support → typical output

→ Need to define the scope and specification for cross-border tax and mobility advisory
Relevant Fenton support: Advisory scope and specification support
What you receive: Written specification covering services required, exclusions, deliverables, performance criteria, and stakeholder requirements.

→ Evaluating whether to appoint a large firm, boutique specialist, or blended model
Relevant Fenton support: Supplier evaluation and benchmarking input
What you receive: Assessment of capability, senior involvement, scope coverage, coordination model, and value for money against defined criteria.

→ Incumbent adviser underperforming or scope is unclear
Relevant Fenton support: Incumbent review and respecification
What you receive: Gap analysis of current provision, identification of missing scope, and recommendation on respecification or retender.

→ Need to understand the difference between advisory, compliance, payroll, and relocation providers
Relevant Fenton support: Scope clarification
What you receive: Written explanation of provider types, what each delivers, and which combination meets the business need.

→Conducting due diligence on a specialist or boutique tax advisory firm
Relevant Fenton support: Due diligence support
What you receive: Checklist and assessment covering credentials, experience, insurance, conflicts, data handling, escalation, and senior involvement.

→ Need to coordinate multiple providers and no single party owns the integrated position
Relevant Fenton support: Multi-adviser coordination assessment
What you receive: Evaluation of current provider landscape, identification of gaps and overlaps, and recommendation on coordination model.

→ Drafting or reviewing an RFP for cross-border tax and mobility advisory
Relevant Fenton support: RFP specification review
What you receive: Review and input on scope, evaluation criteria, scoring methodology, and questions to include. RFP means request for proposals — a formal procurement document inviting suppliers to propose how they will deliver a defined scope of work.

What a proper evaluation needs to cover

A defensible appointment of a cross-border tax and mobility adviser — proportionate to the risk and complexity of the engagement — usually needs to address:

Specification: which services are required, which are out of scope, and what deliverables the business expects
Technical capability: does the provider cover the jurisdictions, tax types, and people-tax disciplines needed
Senior involvement: who will lead and review the work — not just who will be named on the proposal
Coordination: can the provider work alongside existing suppliers, including immigration, employment law, payroll and relocation, or does it require sole appointment
Due diligence: credentials, professional memberships, insurance, conflicts of interest, data handling, and confidentiality arrangements
Value for money: fee structure, scope control, and whether the cost is proportionate to the risk being managed — not simply the lowest price
Performance measurement: what KPIs, service levels, or review mechanisms will apply. KPIs are key performance indicators — agreed metrics used to assess whether the provider is meeting the specification.
Stakeholder alignment: have HR, finance, tax, legal, and the board been consulted on the specification and evaluation criteria
Governance: is the appointment decision documented, the rationale recorded, and the process defensible if reviewed

FAQs

How should procurement or buyer evaluate a cross-border tax and mobility adviser?

1

Evaluate against a defined specification that covers technical capability, senior involvement, scope, jurisdictional coverage, coordination with other providers, due diligence — including credentials, insurance, conflicts and data handling — value for money, and deliverables. The evaluation criteria and their relative weighting should be agreed with key stakeholders — HR, finance, tax, and legal — before the process begins, not after proposals are received.

What is the difference between a tax adviser, payroll provider, and relocation company?

2

A tax adviser determines the tax, payroll, and social security position and advises on obligations, risks, and options. A payroll provider processes payroll calculations, filings, and payments based on the position determined. A relocation company manages practical relocation services such as moving, housing, and settling-in. Cross-border workforce matters often require all three, but the advisory, processing, and practical functions are distinct — appointing the wrong provider type for the wrong scope is a common procurement error.

Can a boutique specialist adviser be suitable for corporate procurement?

3

Yes, where the matter requires senior specialist judgement, cross-border experience, independence, and/or multi-adviser coordination. Procurement should evaluate expertise, senior involvement, governance, professional credentials, insurance, scope coverage, and ability to work with existing corporate providers. Due diligence should be proportionate to the value and complexity of the engagement — a boutique firm may warrant different checks from a large firm, but the evaluation framework should be consistent.

What should an RFP for cross-border tax and mobility advisory include?

4

The specification should cover remote workers, business travellers, international commuters, directors, payroll obligations, social security, pensions, executive relocation, assignment policy, equity and reward, tax equalisation, policy, reporting outputs, escalation process, KPIs, data requirements, fee structure, and coordination with immigration, employment law, and payroll support. Tax equalisation means an arrangement where the employer adjusts the tax cost so the employee pays no more or less than they would have in their home country. The RFP should state the evaluation criteria and scoring methodology, and require proposers to confirm who will lead and review the work — not just the firm's general capability.

When should procurement replace or retender an existing tax advisory arrangement?

5

When the incumbent is not meeting the agreed specification, providing poor value, budget overruns, the scope has changed, stakeholder feedback identifies gaps, the work has outgrown the provider's capability, or the appointment decision is no longer documented or defensible. A structured benchmarking exercise against a current specification — not just a price comparison — is the proper basis for a retender decision.

Credentials and related insights

Fenton’s Employer Advisory Office is led by Mark Abbs, a senior international tax adviser with more than 32 years’ experience, with 14 years as Tax Partner, Head of International and Senior Leadership Team member at a UK Top 8 firm. Over 16 years as a Senior Adviser in Big 4 firms (PwC, EY). He is a Fellow of the Association of Taxation Technicians, an IRS Enrolled Agent, and an accredited expert witness.