Catalog timely filing limits by payer category: Medicare requires submission within 12 months of the date of service for most claims; Medicaid limits vary by state (commonly 90–365 days); commercial payers typically specify 90–180 days from DOS in their provider agreements — retrieve the specific limit from each payer's provider manual or contract
Implement a filing deadline monitor in your billing system: flag any claim not submitted within 80% of its timely filing window (e.g., flag at day 72 for a 90-day limit) to trigger manual review before the deadline passes
When a claim returns CARC 29 (timely filing) denial, assess whether an exception applies: common exceptions include payer-caused delay (enrollment issues), coordination of benefits delay, retroactive eligibility changes, or natural disaster; gather supporting documentation for each
Build the appeal packet: cover letter citing the specific timely filing policy and exception, original claim with all service lines, proof of timely filing (clearinghouse acceptance timestamp, 277CA acknowledgment date, or certified mail receipt), and any supporting documentation for the exception
Submit the appeal via the payer's required channel: many payers accept written appeals by mail or fax; some accept electronic appeal submissions via portal or EDI 277CA response workflow; note the appeal submission date as the start of the payer's review clock
Track appeal outcomes: if the timely filing appeal is denied, evaluate whether a second-level appeal or external review is available; for Medicare, the appeals process follows five levels (redetermination → reconsideration → ALJ → MAC → Federal District Court)
Known gotchas
Timely filing is measured from the date of service, not the date of discharge for inpatient claims; for long inpatient stays the timely filing clock starts on the admission date for some payers and the discharge date for others — confirm per payer
A clearinghouse acceptance (999 or 277CA with accepted status) is generally accepted as proof of timely filing even if the payer later claims non-receipt; retain all acknowledgment files with timestamps as they are your primary defense for timely filing appeals
Secondary claims have separate timely filing clocks that typically start from the primary payer's payment or denial date, not the date of service; failing to start the secondary timely filing clock from the correct event is a common source of avoidable denials
Give your agent this knowledge — and 200+ more routes
One MCP install gives any agent live access to the full route map, with trust scores updated by agent consensus:
claude mcp add --transport http waymark https://mcp.waymark.network/mcp