The Republic of Kiribati first issued official stamps on May 1st, 1981. The stamps consisted of the current Pictorial Definitives overprinted O.K.G.S., which stood for "On Kiribati Government Service."

The announced intention of these stamps were for use of postage by all government agencies including the Post Office and the Philatelic Bureau.

While the stamps were commonly used by the Kiribati Philatelic Bureau and also by some government agencies, other agencies continued to send mail with official stampless covers incorporating a departmental handstamp.

• O.K.G.S is 3.5mm in height
• First period spaced equally between the "O" and "K" and aligned with the bottom of "K"
• Second period close to the "K" and aligned with the bottom of "K"
• Third period centred between the "G" and "S"

• O.K.G.S is 3.0mm in height
• First period is closer to the "K" and is slightly below the bottom of the "K"
• Second period is spaced equally between the "K" and "G" and is slightly below the "K".
• The third period is closer to the "S"