Beyond the Signed Contract: The Mobility Costs UK Service Firms Keep Discovering Too Late

The tender was won on capability, price and a persuasive delivery plan. Eight weeks later the project is slipping because two named engineers cannot lawfully be on site in Rotterdam for more than a fortnight at a stretch, the lead consultant's relocation has created an unplanned payroll obligation in the Netherlands, and the client has noticed that the tooling subcontractor is not covered by the insurance schedule. None of that friction appeared in the bid model.

For UK consultancies, engineering practices, design studios, software houses and agencies, mobility is rarely the headline risk at award stage. It becomes the margin problem afterwards — and it tends to surface in the least convenient quarter of the financial year.

Permission to trade is not permission to be present

Since the UK left the EU free-movement regime, two questions have separated: whether a firm may supply a service, and whether a particular person may be physically present to deliver it. The Trade and Cooperation Agreement provides a framework covering short-term business visitors, intra-corporate transferees, contractual service suppliers and independent professionals. It is a schedule of sector-specific commitments subject to national reservations, not a work permit. A UK national attending a client workshop in the Schengen area is usually travelling under short-stay provisions; billing for productive work on a client site is a different activity in most member states, and several require national authorisation even for short assignments.

The practical lesson is that a delivery model should be designed around the tightest jurisdiction in the portfolio rather than the most accommodating one. Teams rotate. The consultant who was booked for Germany ends up covering a French workstream, and the compliance assumption travels with the person, not the contract.

Posted workers: the rules follow the individual

Where a UK employer sends staff to provide a service in an EU member state, the Posted Workers Directive and its enforcement measures generally apply. In outline, that means host-country terms on remuneration, holiday and working time for the duration of the posting, alongside administrative duties that vary considerably between capitals: notification portals in Belgium, France and the Netherlands, documentary requirements in Germany and Italy, and registration steps in most others. Evidence of social security cover is required as well. The social security protocol in the TCA usually allows a detached worker to remain in the UK scheme for a limited period, but the certificate is not a formality to be completed the week before travel.

Two errors recur. The first is treating posting compliance as an HR task delegated to whoever books the flights. The second is assuming that a short assignment falls outside the rules because the client is not the employer. Neither survives scrutiny.

The Gulf: quotas, sponsorship and the local footprint

The Gulf markets are welcoming to buyers and exacting for suppliers. In the United Arab Emirates, work authorisation is tied to a licensed entity and to quotas influenced by office space and Emiratisation expectations. In Saudi Arabia, the residency system, the Saudisation framework and the regional headquarters programme together shape what a UK firm can credibly promise a client. A frequent mistake is bidding with a UK-resident team on the assumption that a local partner will sponsor them later. Sponsorship is an entity-level capability, not a favour extended after the fact.

Tax follows the people. Service fees paid outbound often attract withholding tax that the client will simply deduct from the invoice, and a team that is present for months rather than weeks can create a taxable presence that the finance function never modelled. Contracts should state gross-up mechanics, and the commercial team should know the number before the price is fixed.

The United States: plan for the cap, not the best case

US mobility is a queuing problem dressed as a paperwork problem. The H-1B route is subject to an annual cap and a selection process that no amount of preparation can guarantee. The L-1 route works for intra-company transferees but requires a qualifying corporate relationship and a year of prior employment. The O-1 route rewards genuinely exceptional profiles and punishes optimism. The B-1 visitor route is a business visitor category: it does not authorise productive work, and using it as a soft alternative is a well-trodden route to difficulty.

Beneath the visa question sits state-level exposure. A consultant present in a state for an extended period can trigger payroll withholding and personal filing obligations, which is why shadow payroll arrangements are standard among firms that deploy people rather than post them. On the revenue side, certain US-source payments to a UK company attract withholding unless treaty relief is claimed properly at the outset.

Tax residency and the 183-day assumption

The UK statutory residence test is more nuanced than the day count that most bid teams quote. Ties, work patterns and family circumstances all matter, and a split-year treatment does not automatically resolve the employer's obligations in both countries. Double tax treaties prevent the worst outcomes but require claims, certificates and, in practice, an adviser who has read the specific article rather than a summary of it.

A pre-bid checklist for cross-border service delivery

• Identify every jurisdiction where a named individual will physically work, not just where the contract is signed.
• Classify each activity as business visit, posting or local employment, and confirm the applicable authorisation route.
• Confirm social security position and the certificate required before departure.
• Check notification and registration duties in each host state, and assign an owner with a deadline.
• Model withholding tax, gross-up and permanent establishment risk in the pricing sheet.
• Confirm professional indemnity and employer liability cover extends to staff working abroad.
• Establish data transfer and confidentiality arrangements for client-site working.
• Price a mobility loading into the day rate rather than absorbing it in overhead.
• Build a substitution clause so that a permit delay does not become a breach.
• Record the client's own compliance obligations — site induction, right-to-work evidence, subcontractor approval.

Pricing the friction rather than discovering it

Mobility cost is predictable. It is simply not predictable by the people who usually build the bid. The firms that handle this well treat jurisdiction mapping as part of solution design: they restrict named individuals to roles that can be delivered remotely, they price a visible mobility line so the client understands what it is buying, and they keep a small bench of locally authorised partners for work that cannot wait for an authorisation to clear.

For a UK services business selling globally, the passport question is not an administrative afterthought. It is a structural constraint on how, where and by whom the work can be delivered — and it deserves a place in the commercial model long before the contract is signed.