X12 823 — Lockbox

Detail of bank-collected lockbox payments to a corporate client: each check or wire received in a collection account is listed with its remittance details, enabling automated AR cash application.

Purpose

A lockbox is a banking service: the corporate client publishes a postal address operated by the bank. The bank opens the mail, deposits the checks, scans the coupons, and the 823 delivers the electronic inventory of the day: amount per received payment, invoice references, dates, OCR remarks. It is the collection counterpart of the 820 on the payer side. Corporates use it for auto-cash application: matching each receipt against the corresponding invoice inside the ERP.

Envelope and structure

The 823 uses the standard triple X12 envelope with GS01 = LB. Minimal 823 covering two lockbox payments on a same day:

ISA*00*          *00*          *ZZ*BIGBANK01      *ZZ*CORPCLIENT     *260513*0500*U*00501*000000823*0*P*>~
GS*LB*BIGBANK01*CORPCLIENT*20260513*0500*1*X*005010~
ST*823*0001~
LB*LB-WIRES-0001*20260512*1*44850.00~
N1*PR*BIG BANK*FI*987654321~
N1*PE*CORP CLIENT INC*FI*111222333~
LX*1~
LS*0100~
RMR*IV*INV-77821**4500.00*4500.00~
DTM*003*20260512~
NTE*RMR*PARTIAL PAYMENT~
LE*0100~
LX*2~
LS*0100~
RMR*IV*INV-77822**40350.00*40350.00~
DTM*003*20260512~
LE*0100~
SE*15*0001~
GE*1*1~
IEA*1*000000823~

Common segments (concept)

• Header — LB Lockbox identifies the lockbox session (number, date, batch count, total amount). N1 Originator (the bank) and N1 Reporter (the client) identify the parties.
• Detail — each received payment opens a loop: LX Header Number, LS Loop Header (code 0100 for the payment loop), RMR Remittance Advice Accounts Receivable Open Item Reference carries remittance details (qualifier IV Invoice, paid amount, original invoice amount). DTM for receipt date and value date, NTE for notes (PARTIAL PAYMENT, NO COUPON, etc.), LE Loop Trailer closes the loop.
• Summary — a single SE.

When you'll see it

The 823 is used by every US corporate that handles high-volume incoming payments: auto insurance, telco, utilities, edtech. Historic lockbox banks (Bank of America, BNY Mellon, JPMorgan Treasury Services, Wells Fargo) deliver one or several 823s per lockbox each day. Specialised Order-to-Cash vendors (HighRadius, Billtrust, Versapay) parse the 823 to feed their auto-cash engines. Modern alternative: BAI2 and NACHA CTX addenda for ACH payments.

Related transactions

• 820 — Payment Order/Remittance Advice (funds movement with remittance).
• 821 — Financial Information Reporting (aggregate balances and movements). See 821 page →
• 810 — Invoice (the invoice whose payment is confirmed by the 823).
• 997 — Functional Acknowledgment. See 997 page →

Documentation

• x12.org/products/transaction-sets — public index, name and code 823.
• stedi.com/edi/x12/transaction-set/823 — public editorial reference, examples.
• Implementation Guide (TR3) — available for purchase on x12.org or via DISA.