Mo. Rev. Stat. § 525.260
525.260 Debts not due may be attached.
525.260. Debts not due may be attached. — Debts not yet due to the defendant may be attached, but no execution shall be awarded against the garnishee for debts until they shall become due.
(RSMo 1939 § 1585) Prior revisions: 1929 § 1421; 1919 § 1871; 1909 § 2438