O.H.M.S.
![Australian official mail, franked](/Images/godic/202501/30/Crash_cover_Khartoum-Alexandria_31Dec19353222.jpg")
![](/Images/godic/202501/30/Official_Paid_Scan3222.jpg")
O.H.M.S., an initialism for On Her Majesty's Service or On His Majesty's Service (depending on the sex of the reigning monarch), is an official franking commonly seen on correspondence from government departments in the United Kingdom, Canada and other countries that share the same monarch as their head of state (now known as Commonwealth realms).