Strong Tower Consulting, LLC is the Minnesota freight technology consulting firm founded by Scott Elliott in 2008. This estimator applies only the numbers you enter. It is general information about billing arithmetic and record assembly. It is not legal advice, and it does not decide what you owe.
Quick answer
Total billed is containers times days past free time times the combined daily demurrage and chassis rate. This model treats appointment outage days, plus one day for each dual-transaction rejection, as dispute-eligible and caps that amount at total billed. Net balance is total billed minus dispute-eligible fees. With the defaults below, total billed is $0.00, dispute-eligible is $0.00, and the net balance is $0.00. Check coverage under 46 CFR 541 and your contract before you withhold any amount.
Dispute-eligible here is a modelling assumption: outage days for each container, plus one combined day per dual-transaction rejection, capped at total billed. Covered charges and invoice compliance under OSRA-22 and 46 CFR 541 depend on facts this page cannot see.
Days when no appointment was available. Modelled as dispute-eligible for every container.
Each rejection is modelled as 1 day of demurrage plus chassis per diem in dispute-eligible fees.
Results from your assumptions
Show the math
- Invoice identifies the billed party, container, billing period, rate, and basis for the charge, as required for covered invoices under 46 CFR 541.
- Tariff, contract, or bill of lading term that authorises demurrage and chassis per diem, with the free time amount stated.
- Free time start, last free day notice, and the date the container was available for pickup or return.
- Appointment availability log for each outage day, with screenshots or portal records kept in original form.
- Terminal or gate outage notices, closure records, and holiday or weekend rules that affect the clock.
- Dual-transaction rejection receipts showing the attempted delivery and return, the reason given, and the timestamp.
- Chassis interchange in and out receipts, chassis number, and any split or flip records.
- Gate in, gate out, empty return, and laden pickup timestamps from the terminal and your ELD or dispatch record.
- Your written dispute notice sent within the billing party deadline, with proof of sending and the amount disputed line by line.
- Payment record for the undisputed net amount, kept separate from the disputed lines.
Note on 46 CFR 541 and OSRA-22: the Federal Maritime Commission demurrage and detention billing rule at 46 CFR Part 541, adopted under the Ocean Shipping Reform Act of 2022 (OSRA-22), sets requirements for covered demurrage and detention invoices, including invoice content and dispute timing. This estimator does not test invoice compliance. This page is not legal advice. Confirm coverage and deadlines with qualified counsel before you withhold payment.
How the model works
Total demurrage billed is containers times the daily demurrage rate times days past free time. Total chassis billed uses the same containers and days with the chassis per diem. Outage eligibility is containers times outage days times the combined daily rate. Rejection eligibility is the rejection count times one combined daily rate, because each rejection is modelled as one day. Eligible fees are the sum, capped at total billed. Net balance is total billed minus eligible fees.
combined_rate = demurrage_rate + chassis_per_diem
total_demurrage = containers x demurrage_rate x days_past_free
total_chassis = containers x chassis_per_diem x days_past_free
total_billed = total_demurrage + total_chassis
outage_eligible = containers x outage_days x combined_rate
reject_eligible = rejections x 1 day x combined_rate
eligible = min(total_billed, outage_eligible + reject_eligible)
net_balance = total_billed - eligible
Open "Show the math" above to see these lines filled in with your current numbers.
Frequently asked questions
How does this estimator split demurrage and chassis per diem?
Total demurrage billed is containers times the daily demurrage rate times days past free time. Total chassis billed is containers times the daily chassis per diem times the same days past free time. Total billed is the sum of the two lines.
What counts as dispute-eligible in this model?
The model treats appointment outage days as dispute-eligible for every container, and treats each dual-transaction rejection as one day of demurrage plus chassis per diem. Dispute-eligible fees are capped at total billed. Eligibility in the model is not a finding that a charge is unlawful.
What is 46 CFR 541 and OSRA-22 in plain terms?
OSRA-22 is the Ocean Shipping Reform Act of 2022. The Federal Maritime Commission demurrage and detention billing rule at 46 CFR Part 541 sets invoice content, timing, and dispute process requirements for covered charges. Whether a charge is covered and compliant depends on the parties, the contract, and the invoice. This page is general information, not legal advice.
What records should a dispute file contain?
Assemble the invoice and tariff or contract term, free time and last free day notice, appointment availability and outage records, gate and interchange receipts, dual-transaction rejection notices, chassis in and out records, and your timely dispute notice. Keep the original timestamps and do not overwrite source files.
Does this estimator decide that I do not owe the net balance?
No. Net lawful balance in this model is total billed minus the dispute-eligible amount you modelled. It is an arithmetic label for planning. The amount actually owed depends on the governing agreement, the billing party, invoice compliance, and the dispute outcome. Get qualified counsel for a legal determination.
Build the dispute file before the invoice arrives.
Strong Tower Consulting provides independent systems architecture, feasibility audits, and engineering roadmaps for motor carriers and freight brokers. Contact our advisory team or call 763-244-1373 to discuss your operational data and evaluate practical implementation paths for your fleet.