Is there a tax when you inherit a condominium?

When a foreigner dies and leaves his condo in Thailand to his children, do they have to pay any inheritance tax? and I read that we have to sell the unit within a year but I do not understand this because we are his children and only heirs and my father owned the condo in his own name, has a last will for the condo, he was not married, nor living with someone. Can you explain.