Inheritance tax on Spanish assets

My mother has £1 million of uk assets And £1 million Spanish assets. She is uk resident. I am uk resident. My sister has Spanish residency but is uk citizen. Assume my mother is creating a Spanish will to take care ok Spanish assets. Her assets are in Canary Islands. Canary Islands children inherit tax free since 2023. In this scenario how would IHT be calculated. My assumption is. Estate is valued at 2 million. For UK IHT, will HMRC consider overseas assets when looking at gross value of estate? Assume £1 million Spanish property is inherited tax free as Spanish law applies. Assume £1 million UK assets is inheritext tax free as nil rate band of 2 parents and residential allowance applies. Unless whole value of estate being £2 million will mean residential nil rate band does not apply.

Hi,
Please contact the Inheritance Tax team for advice.
Inheritance Tax: general enquiries
Thank you.