The budget estimate proposed to donor countries in New York in December showed that for this year and next, the court seeks a total of $93.3 million to try the five currently detained defendants for crimes against humanity and on other charges.
For the years 2012 to 2015, it wants another $103 million to try an additional five former Khmer Rouge figures who have not yet been publicly identified or arrested.
The document, titled Preliminary Budget Estimates 2012-2015, said, "All offices, including the Office of Administration, are anticipated to be closed by the end of 2015."
The Extraordinary Chambers in the Courts of Cambodia, as the tribunal is formally known, began operating in 2007.
Having so far spent more than $100 million, it has concluded the hearing of only one case, that against Kaing Geuk Eau, alias Duch, who headed a torture center in Phnom Penh.
The second case now pending concerns Nuon Chea, who was the Khmer Rouge regime's chief ideologue, Ieng Sary, who was its foreign minister, Khieu Samphan, its nominal leader, and Ieng Sary's spouse Ieng Thirith, who was minister of social affairs.
Their trials are unlikely to start until next year.
According to the budget estimates, the second case involving the four former leaders is expected to be concluded within 2012, whereas the third case, concerning the five unidentified suspects, is expected to be finished by early 2015.
Reach Sambath, spokesman of the ECCC, said it is "optimistic that the donors will consider our proposal seriously."
The Khmer Rouge are blamed for the deaths of at least 1.7 million Cambodians during their rule from 1975 to 1979.