How to collect unpaid invoices in Missouri: 6-month lien window, consent law, and Associate Circuit Court

Missouri's wiretapping statute (Mo. Rev. Stat. §542.402) prohibits intercepting wire, oral, or electronic communications without the consent of at least one party to the communication. The caller's own participation in the call provides that consent, making Missouri a one-party consent state. Missouri businesses and AI tools acting on their behalf can record collection calls without disclosing the recording to the customer. The statute does not require notification, though disclosure is standard practice for transparency.

Missouri's mechanic's lien law (Mo. Rev. Stat. §429.010 et seq.) protects contractors, subcontractors, and materialmen who furnish labor or materials to improve real property. The lien must be filed in the office of the circuit clerk of the county where the property is located within 6 months after the claimant has furnished the last item of labor or materials (Mo. Rev. Stat. §429.080). The 6-month window is one of the longer filing periods in the country, which gives Missouri contractors meaningful time to pursue first-party collection before the lien becomes necessary.

Before filing a Missouri mechanic's lien, the claimant must serve a written notice of intent to file on the property owner at least 10 days before filing (Mo. Rev. Stat. §429.100). This notice must be served personally or by certified mail. Failure to serve the 10-day notice is grounds for invalidating the lien. Subcontractors and materialmen who lack a direct contract with the owner must serve a notice to owner within 10 days of first furnishing -- this is separate from the pre-filing notice and is required to preserve lien rights against the owner.

Missouri Associate Circuit Court small claims handles claims up to $5,000. Filing fees are $32 to $48. Cases are typically heard within 30 to 45 days. No formal discovery is conducted in small claims. For claims between $5,000 and $25,000, the Associate Circuit Court civil docket applies, and attorney representation becomes more common. Claims above $25,000 are handled in Circuit Court. Missouri courts allow pre-judgment interest at the statutory rate from the date the account was due.

Missouri's statute of limitations on written contracts is 10 years (Mo. Rev. Stat. §516.110) -- the longest written contract SOL of any state. This means a 2016 invoice could theoretically still be pursued in 2026. Oral contracts have a 5-year limit (Mo. Rev. Stat. §516.120). Despite the long legal window, practical collection becomes significantly harder after 2 years: customers dispute more aggressively, documentation is harder to produce, and courts weigh the delay against the creditor. Missouri's 10-year SOL is a last resort, not a reason to delay pursuing an invoice.