“What if your contractor gets reclassified as your tax liability all of a sudden?”

This is a question that every company hiring remote workers from the UK or nearby has to consider. A single error in the contractor’s IR35 classification, or the misunderstanding of which nation has the taxing right under a double tax treaty, could cause the HMRC to issue unexpected bills, impose social security requirements, or even increase the risk of the company being considered a permanent establishment (PE).

Today, we will explain in detail the following:

• The real meaning of IR35 in a remote world.
• The role of double tax treaties (DTTs) in peaceful or difficult cross-border work.
• The practical guardrails set for both employers and remote workers.

So, let’s get started!

IR35 & Off-Payroll Rules: Not only typical UK office drama

What is IR35?
IR35 is the UK anti-avoidance regulation that aims to stop “disguised employment” or the use of a Personal Service Company (PSC) or intermediary to look self-employed while actually being in every respect an employee.

If the contractor who works through a PSC had been considered an employee in case of direct payment, then IR35 states: the tax and National Insurance (NI) must be applied as though they were an employee.

Who now determines the status?
Since April 2021, private-sector end clients (unless they qualify as small under the Companies Act) are responsible for determining a contractor’s IR35 status. A “small” company is one that meets two of the three thresholds (turnover ≤ £10.2M, balance sheet ≤ £5.1M, ≤ 50 employees). If a company exceeds those thresholds for two consecutive years, the exemption ends.

If deemed inside IR35, it implies that the client (or the agency) must implement PAYE (i.e., deduct tax & NI) on the “employment” part deemed by the contractor.

Does IR35 apply to remote/overseas contractors?
If a contractor is a non-UK tax resident and performs all services outside the UK, IR35 generally does not apply since there’s no UK-source income. However, if any substantial work is carried out inside the UK, or if there’s a strong UK link (like a UK-based client, branch, or management control), IR35 exposure can arise.

On the other hand, if they ever do services in the UK physically (not just “incidental” activities), they might have to deal with IR35.

The connections & the contractual chain (a UK client, UK presence, UK branch) also play a role in the situation. Even those workers who work remotely from outside the UK might be caught if their arrangement is such that it creates a UK connection.

To sum it up: Working remotely from overseas doesn’t automatically remove you from IR35. Each engagement must be reviewed case-by-case — considering where the services are performed, the tax residency of the contractor, and how the contractual chain is structured.

Why employers should bother with this:
If a client misclassifies, then HMRC can dispute the status, and liable for the company’s unpaid taxes, NI, and penalties may be the payment.

However, international remote work is increasing. The majority of UK companies view overseas contracting as a way to cut IR35 risk — but this cut is only valid if the contractor is actually outside the UK tax and NIC net.

Even when IR35 is ruled out, remote work can still create a Permanent Establishment (PE) in the contractor’s country — meaning the UK company could be seen as having a taxable presence there.

Double Tax Treaties (DTTs): The sharing game

When income is taxable in two countries, Double Tax Treaties (DTTs) determine which nation has the first right to tax and how relief will be granted to avoid double taxation. The UK maintains one of the world’s largest DTT networks, covering 130+ jurisdictions.

Principles that are worth knowing:

• A DTT may state the country that has the primary right to tax employment income, business profits, dividends, etc.\
• Usually, the “residence country” provides relief (via foreign tax credit or exemption) for tax paid in the other country.
• If there is no treaty between the two countries, the domestic laws in the UK may grant the taxpayer the benefit of a foreign tax credit as the sole remedy.

How it works:
Suppose a UK resident works remotely from another country (State X) for an entire year, and both countries claim taxing rights. Under most UK treaties, the UK (as residence state) taxes the income first, and State X provides relief — either by crediting the UK tax or exempting that income. This ensures the same income isn’t taxed twice.

If you paid tax in Country X first, the UK may credit that tax against what you would owe in the UK. If the tax in the UK is higher, you pay the difference; if lower or the same, the tax liability in the UK might be zero.

IR35 Interaction
If a contractor is caught by IR35, the deemed payment is treated as employment income under UK tax rules. However, where another country also asserts taxing rights, relief must be claimed under the applicable Double Tax Treaty to prevent dual taxation.

Practical limits: for employers and remote UK-connected workers

Here’s a checklist and best practices to avoid nasty surprises:

• For Employers / Clients

1. Conduct status assessments
   Don’t make blanket IR35 decisions. Individual assessments of each contractor engagement should be carried out.
2. Get non-UK residency/location documentation
   Document for foreign contractors that they are non-UK tax residents and that they do not undertake substantial work in the UK.
3. Reduce UK interactions/meetings to a minimum
   Reduce the requirement for physical presence in the UK; avoid strict supervision coming from UK offices. This will decrease the chances of IR35 or a UK PE claim.
4. Implement a remote work policy and geographical limitations
   Specify which countries are allowed or forbidden for contractors to work from, and how long they can reside there before their case is subject to additional review.
5. Be cautious about Permanent Establishment (PE) risks
   In case IR35 is already ruled out, the foreign worker working remotely could still be the reason for the UK company to have a taxable presence in that foreign country.
6. Apply contract clauses with indemnities
   Allow the contractors to be responsible for the legalities of their location. Make them convey the place of their work, the legalities, and indemnify the company for any false steps.

Always document your IR35 and tax assessments, residency evidence, and travel records. HMRC expects contemporaneous documentation to support your classification and treaty claims.

• Applicable to Remote Workers / Contractors

1. Establish your tax residency
   Apply the UK’s statutory residence test. You can become a UK tax resident by spending 183+ days, having a home, or having ties in the UK.
2. Keep accurate records
   Keep track of the days you spent in each country, where you worked, and write confirmations of your work location. All this will help you defend your position in the event of an audit.
3. Claim relief under the DTT or the UK unilateral relief
   In the case of paying tax abroad, tax relief or exemption should be claimed in the UK to eliminate that amount from the UK tax liability.
4. Reduce UK presence and duties
   Limit your trips to the UK to perform tasks related to your contract and choose to be fully remote in order to minimize the risk of being charged by the UK.
5. Get professional cross-border tax advice
   These rules are complicated, fact-sensitive, and changing. Do not base your actions on general assumptions.

Real-world scenarios & “what ifs”

• A US software company hires a Polish programmer. The Polish programmer does not travel to the UK, is not a UK resident, and all the work is performed in Poland. Therefore, IR35 is unlikely to apply in this case. The client’s IR35 exposure is very low. However, the client still has to assess PE risk in Poland.
• A UK customer has a contractor in Spain who sometimes comes to London. The contractor’s occasional presence in the UK may mean he/she will be taxed in the UK and pay NIC for those days. IR35 assessment should take into account local work, as well as relief under the DTT for Spain–UK.
• An employee from the UK wants to stay in his home country (e.g., India) for 9 months and work remotely. The employee’s salary is still UK employment income, but now India can also tax him/her on the income earned from their duties performed there. The UK tax regime will consider DTT relief. Local payroll or withholding obligations for the employer may arise.

Final takeaways

• IR35 is a significant risk for UK contracts and must be resolved by analyzing each case individually — you cannot “IR35-proof” everything with one rule.
• The fact of being remote or overseas will help, but it will not necessarily mean that you are completely free from the UK tax or IR35 exposure.
• Double tax treaties are your protection. Be smart in using them to avoid double taxation.
• Good documentation, defined roles, clear policies, and audit trails are your strongest defense.
• Always consult local and cross-border tax guidance — nothing can substitute fact-specific advice.

For any cross-border case, also review HMRC’s CEST tool (Check Employment Status for Tax) — it can help structure your initial assessment, though it’s not legally binding in tribunal proceedings.

Next up in our Country Deep Dives series: Discover how Germany, France, and the Netherlands are redefining remote work with their unique labor, tax, and compliance frameworks.

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