Inheritance from the US

I am due to receive inheritance from US assets due to the death of my mother (who was domiciled in the UK despite being an American citizen with assets in the US). How do I ensure that I declare this as capital and not as income? I have called the inheritance tax phone line but did not get a clear answer, there appeared to be confusion relating to it being a foreign asset Thank you!

Hi rose123,
You are not taxable on the estate you inherit from your late mother.
Inheritance tax is paid by the estate of the deceased.
You may be subject to capital gains tax should you dispose of any assets you inhertied, such as property.
Have a look at the guidance on Capital Gains Tax  here:
Capital Gains Tax
Inheritance tax here:
How Inheritance Tax works: thresholds, rules and allowances.
Thank you.