Hi,
Please have a look at the guidance at
Negligible value claims and agreements and how to claim NVC.
If you own the shares and claim NVC, you cannot then gift them to someone else.
When the NVC is agreed and converted to a loss, you can set the loss against your other income.
As the shares have no value, they cannot impact inheritance tax.
If you have claimed NVC, then you are declaring the shares as worthless. They cannot then increase in value.
Thank you.