Hi Vivienne

Welcome to Communities.

Sure our regular contributor Ray will be along to advise shortly who has vastly more current expertise than I do.

My own view for what it’s worth is that you absolutely require access to specialist data research organisations guidance such as Employment Conditions Abroad or Mercer’s.

Your assumptions about NL and UK peer group salaries may or may not be correct- I have no idea but the sources mentioned will confirm this or otherwise, and go on to analyse such as comparative living costs  in each country and comparative taxation and social security arrangements  to name just a couple of key aspects to consider out of very many that are relevant in order to base your package on reality based on much independent objective expert research as opposed to someone’s subjective impressions and assumptions.

Thus I’d strongly recommend that your organisation commissions this kind of advice - unless of course it is well-used to producing similar in-house. It won’t come cheap, but there’s not much reliable or safe alternative.

HI Vivienne, and welcome to the forums Big question, so long post...

I am assuming the person is already an employee of your company/group in the Netherlands. If not, then it will not be possible to retain them in NL social security system and bring them to the UK as a "posted worker" - this would be a recruitment by a UK company for work in the UK and therefore UK social security.

If it's an internal group mobility, and you want to keep them in the Netherlands social security system and the NL company pension scheme, then they will need to remain an employee of the NL company, and come as a "posted worker". As an employee of a foreign company they can't be enrolled in your UK pension scheme so auto-enrolment would not apply - also check with the NL pension provider that they can stay in the NL company scheme whilst abroad - probable but not 100% certain)

From a payroll point of view it it would be simpler for the current NL employer to keep them on NL payroll and bill you for actual costs, they would also action any special payments like moving in allowance.

Two documents need setting up

1. an addendum to their existing NL contract, seconding them to you UK operation indicating revised key elements contractual conditions applicable during the secondment, and what wiill happen at the end of it.
2. An intercompany agreement between your UK company and the NL employer, clarifying who is responsible for what, how billing will happen, and how the secondment can be ended (if an early end is needed)

The UK company will need to set up arrangements for the person to be UK tax registered and accompanied for their annual declaration (as you say) - get proper professional advice from a firm that has experience in this area - don't just use any old chartered accountant.

If whilst the person is in the UK you want to align the level of salary the local market, you will only be able to do that if the UK level is higher ((probable in London) - and you could pay a temporary supplement to get to the target level, a supplement that ends when the assignment ends (you're still likely to face negotiations when they return, but they will be easier if the amount is clearly identified as an "extra". 

Make sure that you have clear gross to net figures of current earnings and what they will have net whilst in the UK - that will help build trust and avoid any nasty surprises. Make sure they fully understand about London cost of living that they will have to meet from their net earnings, which will be significantly higher than in the Netherlands (particularly transport and housing).. 

If the person is single with no children, it will be a lot easier - if family is involved make sure that the spouse and children receive some sort of accompaniment or buddying in the first weeks/months - many assignments fail because the spouse/family is not properly prepared.

Detailed excellent advice (at a price) can be got from companies like Employment Conditions Abroad - I would recommend consulting them, because the cost of getting it wrong can be horrific in human, tax and administration terms