Only two of these are yours to originate

Most SEC codes are not options for a business sending payments. Some are debit-only, several exist purely to convert paper cheques, and a handful carry no money at all — banks and ACH operators generate those. If you are paying employees or vendors, the real choice is between two codes, and CCD versus PPD walks through which one fits.

Every SEC code

Code	Name and use	Parties	Direction	In this generator
CCD	Corporate Credit or Debit Entry. The corporate entry class: payments between two business accounts, such as paying a vendor or moving money between a company's own accounts. Carries at most one addenda record.	Business to business	Credits and debits	Yes, credits
PPD	Prearranged Payment and Deposit Entry. The consumer entry class, used where an organisation pays or debits an individual under an authorization arranged in advance. Payroll direct deposit is the archetypal PPD credit.	Business to consumer	Credits and debits	Yes, credits
CTX	Corporate Trade Exchange. Like CCD, but carries up to 9,999 addenda records so a single payment can settle many invoices with full EDI remittance data attached.	Business to business	Credits and debits	No — Multi-addenda format
WEB	Internet-Initiated / Mobile Entry. Debits authorized by a consumer online or in an app. Credit WEB entries exist, but only for person-to-person transfers — a business cannot pay someone with a WEB credit.	Consumer	Debits, and credits only between consumers	No — Debit-side authorization rules
TEL	Telephone-Initiated Entry. Debits authorized by a consumer over the phone, with recorded or written-confirmation authorization requirements.	Business to consumer	Debits only	No — Debit only
IAT	International ACH Transaction. Any entry where part of the payment goes to or comes from a financial agency outside the United States. Carries mandatory addenda identifying every party for sanctions screening.	Cross-border	Credits and debits	No — International, extra addenda required
CIE	Customer Initiated Entry. A bill payment the consumer originates themselves through their own bank's bill-pay service, rather than one the biller pulls.	Consumer to business	Credits	No — Originated by the consumer's bank
ARC	Accounts Receivable Entry. Converts a paper cheque received by mail or at a dropbox into an ACH debit.	Business to consumer or business	Debits only	No — Cheque conversion, debit only
BOC	Back Office Conversion Entry. Converts a cheque taken at the point of sale into an ACH debit during back-office processing rather than at the counter.	Business to consumer or business	Debits only	No — Cheque conversion, debit only
POP	Point-of-Purchase Entry. Converts a cheque into an ACH debit at the counter, with the cheque handed back to the customer.	Business to consumer or business	Debits only	No — Cheque conversion, debit only
RCK	Re-presented Check Entry. Re-presents a cheque that bounced for insufficient or uncollected funds, as an ACH debit instead of a second paper presentment.	Business to consumer	Debits only	No — Cheque re-presentment, debit only
XCK	Destroyed Check Entry. Used when the physical cheque has been destroyed or lost and only the MICR line survives.	Business to consumer or business	Debits only	No — Cheque conversion, debit only
POS	Point of Sale Entry. Debits initiated at an electronic terminal using a card issued against a consumer account.	Business to consumer	Debits	No — Terminal-initiated, debit
MTE	Machine Transfer Entry. Entries arising from a consumer's use of an ATM.	Consumer	Debits	No — Terminal-initiated
SHR	Shared Network Transaction. Entries initiated through a shared electronic terminal network.	Consumer	Credits and debits	No — Terminal-initiated
TRC	Truncated Entry. A cheque truncated at the point of collection and carried as an ACH debit.	Business to consumer or business	Debits only	No — Cheque truncation, debit only
COR	Notification of Change. Carries no money. The receiving bank uses it to tell you that an account or routing number you sent was wrong but was posted anyway, so you correct it before the next payment.	Bank to originator	Non-monetary	No — Non-monetary, sent by the bank
ACK	ACH Payment Acknowledgment. An acknowledgement that a CCD credit was received. Optional, and rarely used outside established trading relationships.	Business to business	Non-monetary	No — Non-monetary
ATX	Financial EDI Acknowledgment. The CTX equivalent of ACK.	Business to business	Non-monetary	No — Non-monetary
ADV	Automated Accounting Advice. Accounting information an ACH operator provides to financial institutions. Originators never create these.	ACH operator to bank	Non-monetary	No — Non-monetary, operator-generated
DNE	Death Notification Entry. A federal agency notifying a bank that a benefit recipient has died. Federal government use only.	Federal agency to bank	Non-monetary	No — Federal government only
ENR	Automated Enrollment Entry. Enrols someone for federal direct deposit electronically. Federal government use only.	Bank to federal agency	Non-monetary	No — Federal government only

Where the code sits in the file

The SEC code occupies positions 51–53 of the batch header record, one per batch — which is why a file cannot mix entry classes. The annotated ACH file format guide shows the field in a real record, and supported formats lists what else the generator will and will not write.

Sending an entry under the wrong class has consequences beyond tidiness: debiting a consumer account with a corporate code is exactly what return code R05 exists to reject, as the ACH return code list sets out.