How long does it take to approve my application for tax relief for moving my personal belongings from the EU to the UK

Question

I am going to transfer my normal place of residency from the EU to the UK. For this I need to move most of my my personal belongings over the border. The UK offers a ‘transfer of residence’ (ToR) relief on tax and duty for personal belongings. For this, I need to apply to HM Revenue & Customs (HMRC) to claim relief. This application requires me to create a more or less detailled list of all the belonings that I plan to transfer. Since I do not yet know what I will transfer, I have the following question:

Question

How long before crossing the border should I make this application? In other words, how long does it usually take HMRC to approve the application? Would it be sufficient to apply, say, one week before the transfer?

I was unable to find this information on GOV.UK.

Side question: is it a good/bad idea to put things on the list that I might eventually decide not to transfer? In this way I could create a list right now that might be "too long" though.

Answer 1

Having finishd the application, the following information was shown to me (emphasize mine):

What happens next

We will contact you by email or telephone within 15 working days to let you know if your application is approved, or to ask for more information. If we need more information

This was also told to me by phone prior to the application (I called the HMRC service line, which had no longer waiting time every time I called).

The following might also be relevant for the side questions:

If we approve this application, we will email a Unique Reference Number (URN). You can then use this URN to make changes, including adding an animal health certificate.

Apparently one is allowed to make changes to the list after approval. It is not clear to me whether these changes have to be approved again and whether this will take again several days.

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Update

In actuallity, I got my answer within a week. I had to provide further evidence. After having sent that by mail, the application was then approved the same day maybe two hours later.