Where the amount paid for a property is known but the amount actually paid on account of the site is not known, the cost of the site at the time of its acquisition shall be determined by the head of the department by comparing it with similar land, the value of which at the time of the acquisition of the site in question can be ascertained from the record of the district or other government offices. If the cost of the site cannot be so determined, it may be taken to be that proportion of the book-value of the house which the present market value of the site, as assessed by the district officer, bears to the present market value of the whole premises.
