about Tin number directive (Addis Ababa)

anyone knows about the lastest Ethiopian government directive on TIN number? We are required by the Ethiopian government to put our customers' TIN number on every VAT receipt we issue. I knew this from our customers, counterparts and ministry of trade. I have searched many places like ERCA office in Megnagna and Selam printing house for the written evidence but i cannot find it.
anyone knows where to find it? very appreciate it if anyone can provide more information on this.
Now it is more difficult to do business because of various government policy like this one.