Employee leaving the UK - is CA3821 the correct form for this situation?

Hello, we have an employee, a British citizen. who is relocating to Denmark this summer. He will continue to work for us from there. As he will be working there for more than 25% of the time, we will make insurance contributions to Denmark, not the UK. I have been advised by HMRC that we must complete CA3821, but that is for employees that are being sent abroad and who will be returning, to continue making employer NIC contributions, but he is relocating permanently. What do we need to do to notify HMRC that his situation is changing and to stop making employer NIC contributions, so we don't pay twice, to the UK and also to Denmark? Thanks.

Hi,
Please see 2025 to 2026: Employer further guide to PAYE and National Insurance contributions section 4.5 for more information on this.
Thank you.

Thanks, 4.5 doesn't mention CA3821, so I assume that advice was incorrect and we don't fill that in. Most of 4.5 is about employees coming here, not those leaving the UK, except the 'employees working abroad' link which leads to a section about issuing a letter to the employee when they go abroad but, apart from the employee completing form P85 to get a tax code, we, the employer, do not need to do anything; is that correct? A further link says an employer's liability to pay social security contributions follows the liability of the employee; HMRC have already confirmed to him that he will not pay here. I can’t find anything that tells me, as the employer, what we have to do to inform HMRC, or do we do nothing except change the tax code to NT, when that is confirmed? Thanks.

Hi IW,
Yes as per the following guidance link Paying National Insurance if you're going to work in the EU, Gibraltar, Iceland, Liechtenstein, Norway, or Switzerland:
If you leave the UK to work in the EU, Gibraltar, Iceland, Liechtenstein, Norway or Switzerland, you will only pay into one country’s social security scheme at a time.
You will usually pay social security contributions (National Insurance in the UK) in the country you are working in.
As an employer, your liability to pay social security contributions will follow the liability of the employee concerned.
You have stated this guidance has already been confirmed by HMRC, I assume the individual spoke with the NI helpline.
As advised by my colleague, you would change the individual's category letter to X and update the empoyee's address to the address in Denmark.
If you have any further questions regarding NI at all, please contact our NI International Caseworkers on 0300 200 3500.
Thank you.

Thanks for your help.