The fall is a drop of 1.2 dollars since the end of the first quarter, where the debt stood at a peak of 14.7 billion dollars.
Since then, the domestic debt has been on a slow decline, crossing the 13.6 billion dollars mark the other week before falling further to the current level.
CBK data showed the drop was due to a flat sale of Treasury bonds in the past weeks, which account for 78.3 percent or 10.2 billion dollars of the total debt.
The last Treasury bond was put on sale on August 20 and was worth 194 million dollars. CBK received bids worth 188 million dollars but accepted only 109 million dollars at an interest rate of 15 percent.
Most of the bonds issued in the past few months have been massively subscribed due to a rise in interest rates as investors seek to cash in on the high yields.
A move by the regulator to raise its benchmark rate by 3 percent, to stand at 11.5 percent as it sought to mop up excess cash in the market to stem the free fall of the local currency against the major world currencies led to the increased interest rates.
The value of Treasury bills, on the other hand, stands slightly at over 2.8 billion dollars, a drop from 3.3 billion dollars at the beginning of the year.
Last week, the Central Bank put on sale Treasury bills worth 107 million dollars. The bank received bids worth 31.3 million dollars for its 29.1 million dollars 91-day bills.
However, while the 91-day bill attracted a subscription of 107 percent at an interest rate of 11.5 percent, the 182 and 364 days bills performed poorly, raising 12 million dollars and 18.3 million dollars respectively.
Commercial banks hold 57 percent of the East African nation's domestic debt. This is a rise of about 3 percent in six months for the financial institutions, which are the biggest local lenders to the government.
East African nation's public debt load stands at 26.2 billion dollars or 52 percent of the Gross Domestic Product (GDP).
Last week, Treasury said it intended to cut the public debt to about 45 percent of the GDP by reducing the fiscal deficit.
"The level of public debt as at now is sustainable. It would be untenable if it exceeds 74 percent but our aim is to bring it down to about 45 percent in two years," said Geoffrey Mwau, Treasury's director-general for budget and economic affairs.