inheritance
OK, so the sister has no husband or children. Her only relative is her surviving brother.
She owned a half-share of a piece of land with him. No will made.
I AM NOT AN EXPERT, but it seems he would automatically inherit the land, as he is the only relative.
As to tax, well he may have to then pay Capital Acquisitions Tax (CAT), as he has just acquired the asset. This depends on the value of the land.
He can inherit (or be gifted) up to about €45,000 tax-free from a sibling. After that, he would pay CAT at 20%.