I opine that To have an efficient inheritance tax system, Thailand needs clear cut gift tax law which currently, Thailand is lacking. Few people report gift and pay tax law on their personal return. Property can pass from one person to another unnoticed.
Nowadays, many people can predict how long they will live. If inheritance tax is implement, people can simply avoid it by passing the wealth to their loved ones near the end of their life because in practice gift tax is often not collected.