Okla. Stat. tit. 12 § 1186
No judgment shall be rendered upon a liability of the garnishee arising --
First, By reason of his having drawn, accepted, made, endorsed or guaranteed any negotiable bill, draft, note, or other security.
Second, By reason of any money or other thing received or collected by him as sheriff or other officer, by force of an execution or other legal process in favor of the defendant.
Third, By reason of any money in his hands as a public officer, and for which he is accountable to the defendant merely as such officer.
Fourth, By reason of any money or other thing owing from him to the defendant, unless before judgment against the defendant it shall become due absolutely and without depending on any future emergency. Judgment may be given for any money or other thing owing, although it has not become payable, in which case the garnishee shall not be required to pay or deliver it before the time appointed by the contract.
Okla. Stat. tit. 12, § 1186