What Is Shadow Payroll? A UK Guide for Employers

Shadow payroll is a parallel payroll run in the host country for an employee who stays on their home-country payroll while working abroad. It calculates and reports host-country income tax (and sometimes social security) on their pay and benefits, without paying the salary twice. In the UK, HMRC expects it whenever PAYE is due on an internationally mobile employee.

Last reviewed: November 2026

AgileHRO, an Employer of Record and global payroll and mobility provider headquartered in Singapore, runs shadow payrolls for companies moving people between APAC, LATAM, Europe and the UK. This guide covers how it works in the UK, when you need one, and when you don’t.

How does shadow payroll work?

The employee keeps being paid in full by their home employer. A second, “shadow” payroll in the host country calculates the tax due there, reports it to the host tax authority and pays it over. No net salary moves through the shadow payroll.

Here is the typical monthly cycle:

1. The home payroll pays the employee as normal, in the home currency.
2. Home HR sends the host payroll provider the month’s gross pay, bonuses, allowances and benefits (housing, school fees, tax-equalisation payments).
3. The shadow payroll converts those amounts and calculates host-country withholding.
4. The host employer, or its payroll provider, files the return (in the UK, a Full Payment Submission) and pays the tax to the host authority.
5. The home payroll adjusts, if needed, so the employee isn’t taxed twice on the same income. Credits for foreign tax are claimed under the relevant double taxation agreement.

When do you need a shadow payroll in the UK?

You need one when an employee paid from overseas creates a UK PAYE obligation and no HMRC arrangement switches it off. Under HMRC’s guidance on globally mobile employees and PAYE, if an overseas employer with no UK presence sends someone to work for a UK entity, “that entity must operate PAYE” on their PAYE income.

Common triggers:

• Secondments into the UK of more than 183 days in a 12-month period.
• Short-term visits that don’t meet HMRC’s business visitor criteria, for example where the UK company bears the cost.
• Employees who move back to their home country but are still paid UK-sourced income, such as deferred bonuses or share awards.
• Tax-equalised assignees, where the employer pays the UK tax on the employee’s behalf.

What are the UK short-term business visitor rules?

HMRC’s EP Appendix 4 arrangement lets employers disregard PAYE for some visitors from treaty countries. It only applies when the employee is resident in a country with a double taxation agreement and is expected to stay in the UK for 183 days or less in any 12-month period, according to HMRC’s PAYE82000 manual.

Days in the UK	What HMRC requires under Appendix 4
1–30	Nothing, unless the visit is part of a longer stay of 60 days or more
31–59	PAYE can be disregarded if there’s no formal UK employment contract and the days aren’t part of a longer period
60–90	PAYE can be disregarded if you report by 31 May after the tax year end and confirm the UK company doesn’t bear the cost
91–150	As above, plus a residence statement from the overseas tax authority
151–183	A named individual application to HMRC once more than 150 days is likely
Over 183	Appendix 4 doesn’t apply. Run PAYE, usually through a shadow payroll

Two points catch employers out. For named employees present 60 days or more, the UK entity must not ultimately bear their pay. And some treaties, Italy’s for example, count 183 days in a tax year, not any 12-month period. Track UK workdays centrally from day one; HMRC expects employees not to spend more than 30 days intermittently in the UK in a 12-month period without reporting them.

How does tax equalisation affect a shadow payroll?

Tax equalisation means the employer pays the employee’s host-country tax so take-home pay stays roughly the same as at home. That tax payment is itself taxable income, so the shadow payroll has to gross it up.

HMRC’s EP Appendix 6 arrangement (PAYE82002) is designed for this. The employer:

1. Applies to HMRC and signs an agreement to operate the arrangement.
2. Estimates the year’s cash earnings and non-cash benefits, grossed up for tax.
3. Pays one-twelfth of the estimated PAYE each month (or quarterly, if five or fewer employees are covered).
4. Reviews the estimate between December and April.
5. Settles any balance through the employee’s Self Assessment return, paying additional tax by 31 January after the tax year end.

Without an agreed arrangement, you run standard monthly PAYE on grossed-up figures. That works, but it means chasing benefit values from the home country every month.

Does shadow payroll cover social security too?

Sometimes. Income tax and social security follow separate rules. A UK employee sent temporarily to an EU country for up to two years can stay in UK National Insurance if HMRC issues a certificate of coverage (A1), according to GOV.UK guidance on working in the EU. In that case, the EU host shadow payroll handles income tax only.

Where no certificate or social security agreement applies, the shadow payroll may also need to calculate host-country contributions. Check HMRC’s guidance on a new employee coming to work from abroad for the UK side.

Shadow payroll vs split payroll vs Employer of Record

These three solve different problems. Pick based on who employs the person and where they’re paid.

Model	Who employs	Where salary is paid	Best for
Shadow payroll	Home employer	Home country only	Assignments and secondments where the employee keeps their home contract
Split payroll	Home employer, sometimes plus host entity	Partly home, partly host	Long assignments where the employee needs local-currency pay for local costs
Employer of Record	EOR’s local entity	Host country	Permanent hires or long relocations where you have no entity

If an “assignment” has no end date, it’s probably not an assignment. Moving the person onto a local contract through an Employer of Record is often cleaner than running a shadow payroll indefinitely. The EOR vs entity tool helps you test that.

Worked example: a Singapore SaaS sends an engineer to London

A Singapore SaaS company sends a senior engineer to London for seven months to stand up a UK customer team. She stays on the Singapore contract and payroll. The company tax-equalises her and pays for a London flat.

• 183-day test: seven months is over 183 days, so Appendix 4 is off the table from the start.
• UK PAYE: the UK subsidiary hosting her operates PAYE through a shadow payroll. Each month it reports her Singapore salary, the housing benefit and the grossed-up tax-equalisation payment.
• Arrangement: with a full-year estimate available, the company applies for Appendix 6 instead of collecting figures from Singapore monthly.
• Year end: her UK Self Assessment return trues up the estimate, and the company pays any balance by 31 January.
• Home side: Singapore payroll keeps paying her net salary. The company checks her Singapore tax position, including any tax clearance on departure, with IRAS.
• Immigration: she needs the right UK visa before she starts work. The visa and immigration navigator shows the routes.

Three teams usually touch this case: immigration, home payroll and UK payroll. When they sit with three different vendors, the monthly data handoff in step 2 is where errors creep in.

How do you set up a shadow payroll?

Plan it before the employee lands, not after the first payslip.

1. Map the assignment: dates, expected UK workdays, who bears the cost, and whether the person is tax-equalised.
2. Check the treaty position: confirm the home country has a double taxation agreement with the UK and how it counts the 183 days.
3. Decide on an HMRC arrangement: Appendix 4 for short business visitors, Appendix 6 for tax-equalised assignees, or standard PAYE.
4. Register for PAYE in the UK if the host entity doesn’t already operate it.
5. Agree the data feed: what home payroll sends, in what format, and by which day each month.
6. Run the first cycle and reconcile: compare the shadow figures with home payroll before the first FPS goes in.
7. Close out: plan for trailing income such as bonuses and share awards that vest after the employee leaves.

Where AgileHRO fits

AgileHRO runs EOR, global payroll and mobility under one relationship. For a shadow payroll, that means the same team holds the visa file, the assignment terms and the host-country payroll, so the monthly data handoff happens inside one provider. Our global payroll and global mobility teams are on the ground in the UK, Singapore, Germany, Brazil and the rest of our core markets. We handle the awkward cases: tax-equalised assignees, multi-country rotations and people moving between APAC, LATAM and Europe.

Want to see what an assignment costs before you commit? Run the numbers in the Employment Cost Calculator or book a demo.

This article is general information, not legal or tax advice; check your specific case with a qualified adviser.