5.14 NACH file format reference

NACH (National Automated Clearing House) is the NPCI-operated bulk-debit / credit infrastructure. Lenders use NACH for collecting EMI / loan repayments via pre-authorised mandate.

The NACH file format is fixed-width with delimited records following NPCI’s specifications. This page is the engineer’s quick reference.

Authoritative source: NPCI’s NACH Procedural Guidelines and the NACH 2.0 File Format Specifications (issued and updated periodically). Always cross-reference the current version on NPCI’s site before implementing — NPCI periodically updates field widths and codes.

NACH overall flow

1. Lender holds active mandate (paper NACH or eNACH) for borrower's bank account.
2. Lender generates presentation file for tomorrow's debits.
3. Lender submits file to sponsor bank by daily cut-off.
4. Sponsor bank submits to NPCI.
5. NPCI processes overnight; routes to destination banks.
6. Destination banks attempt debit on settlement date.
7. NPCI returns ack file to sponsor bank next day.
8. Sponsor bank forwards ack file to lender.
9. Lender processes acks: success or bounce per row.

Daily cycle. Most banks have late-evening cut-off (e.g., 15:00 – 18:00 for files presented for next-day settlement).

File types

The lender exchanges these file types with the sponsor bank:

File	Direction	Purpose
Mandate request	Lender → Bank	Activate new mandate (one-time, for paper mandates)
Mandate response	Bank → Lender	Mandate activation result
Presentation file	Lender → Bank	Daily batch of debits to attempt
Inward presentation acknowledgement	Bank → Lender	Sponsor bank confirms receipt
Return file (settlement acknowledgement)	Bank → Lender	Per-debit success / bounce with reason codes
Reversal file	Bank → Lender	Reversal of a previously-settled debit (rare)

Presentation file structure

The presentation file has three record types:

• Header record (1 per file).
• Detail records (1 per debit).
• Trailer record (1 per file).

All records fixed-width; padding spaces / zeros as per spec.

Header record (illustrative; verify against current NPCI spec)

Position	Width	Field	Description
1	1	Record type	1 for header
2 – 5	4	Transaction code	NACH transaction code (e.g., 0067 for retail debit)
6 – 14	9	Sponsor bank IFSC prefix	Sponsor bank routing
15 – 26	12	User number	Lender’s NPCI-assigned User Number
27 – 50	24	User name	Lender’s NPCI-registered name
51 – 58	8	Settlement date	DDMMYYYY of intended settlement
59 – 70	12	Product code	NPCI product code
71 – 95	25	Filler	Spaces

(Exact widths per current NACH spec; the above is illustrative structure.)

Detail record (illustrative; verify against current spec)

Position	Width	Field	Description
1	1	Record type	2 for detail
2 – 17	16	UMRN	Unique Mandate Reference Number from mandate registration
18 – 26	9	Customer reference number	Lender’s internal reference (loan ID etc.)
27 – 37	11	Customer account number	Borrower’s bank account (right-aligned, zero-padded)
38 – 48	11	Amount	Amount in paise (right-aligned, zero-padded; 000010000 = ₹100.00)
49 – 70	22	Customer name	Borrower’s name (left-aligned, space-padded)
71 – 81	11	IFSC	Borrower’s bank IFSC
82 – 92	11	MICR code	Borrower’s bank MICR code
93 – 102	10	Settlement reference	NPCI-assigned (lender leaves blank)
103 – 110	8	Date	Settlement date (same as header)
111 – 130	20	Filler	Spaces

Trailer record

Position	Width	Field	Description
1	1	Record type	7 for trailer
2 – 11	10	Total record count	Excluding header / trailer
12 – 26	15	Total amount	Sum of detail amounts in paise (right-aligned, zero-padded)
27 – 50	24	Filler	Spaces

Sample file (illustrative)

10067SBIN00000001234567890123XYZ NBFC PRIVATE LIMITED       11052026PRODCODE0001
2HDFC0001234ABC123456000001234500001500000Sundar Textiles Pvt Ltd HDFC0001234123456789                                                            11052026
2HDFC0001234XYZ987654000005678900000750000Ravi Enterprises       HDFC0005678987654321                                                            11052026
70000000020000000000022500000

(Whitespace / padding adjusted; actual lines are exact-width.)

Return file structure

Bank returns per-debit outcome:

Position	Width	Field	Description
1	1	Record type	2 for detail (one row per attempted debit)
2 – 17	16	UMRN	(echo)
18 – 26	9	Customer reference number	(echo — lender uses this to map back)
27 – 28	2	Return code	00 for success; otherwise a bounce reason code
29 – 50	22	Return reason text	Human-readable reason
…			Other echo fields

NACH return / bounce reason codes (illustrative subset)

Always verify against current NPCI procedural guidelines:

Code	Reason	Lender action
00	Success	Process repayment
01	Funds insufficient	Apply bounce fee; re-present per policy
02	Account closed	Mark mandate inactive; contact borrower
03	Account does not exist / wrong account	Mark mandate inactive; verify borrower
05	Payment stopped by drawer	Mandate likely revoked unilaterally; contact borrower
09	Other reasons (technical)	Re-present
10	Connectivity / format / technical	Re-present
21	KYC not done	Borrower’s bank-side issue; contact bank
25	Different from KYC name	Verify mandate; may need re-registration
30	Mandate inactive at customer’s bank	Mandate cancelled by borrower; contact
42	Mandate not found	Mandate may have lapsed; verify validity
..	Various other codes	Per spec; lender’s adapter has full mapping

Always refer to NPCI’s current bounce-reason-code matrix — codes are updated periodically and new codes added for new failure modes.

Re-presentation policy

NACH allows re-presentation after a bounce per NPCI rules. Common pattern:

Bounce reason	Re-present?	When
Funds insufficient (01)	Yes	After 1 – 3 days; cap at 2 – 3 attempts per cycle
Account closed (02)	No	Mandate dead; contact borrower
Stopped by drawer (05)	No	Borrower revoked; contact
Technical (09, 10)	Yes	Next day
Mandate inactive (30, 42)	No	Re-register mandate

Lender’s bounce-handling logic encodes this matrix.

Timing and cut-offs

NPCI’s NACH cycle is T+1 settlement with these checkpoints:

• Lender cut-off to sponsor bank: typically 15:00 – 18:00 for next-day settlement.
• Sponsor bank cut-off to NPCI: typically 19:00 – 20:00.
• NPCI processing: overnight.
• Settlement on T+1 during the day.
• Ack file: returned to sponsor bank typically by T+2 morning.
• Lender receives ack: by T+2 mid-day typically.

Lender’s daily batch (5.8) is built around these timings.

Mandate file structure (paper NACH mandate registration)

For paper-based mandate registration (still common for some segments):

• Lender uploads scanned paper mandate to sponsor bank with a structured metadata file.
• Sponsor bank processes; returns UMRN on activation or rejection reason.

For eNACH (Aadhaar / Debit card / Netbanking), mandate registration is API-based and faster.

Lender implementation notes

Sponsor bank choice

Different sponsor banks have slightly different:

• File format variants (within NPCI spec).
• Cut-off times.
• API vs SFTP submission.
• Ack format / timing.

Document per-sponsor-bank quirks in the NACH adapter.

File integrity

• Total amount in trailer must equal sum of detail amounts.
• Record count in trailer must equal detail count.
• Sponsor bank rejects on any integrity failure.

Idempotency

The lender’s customer reference number must be unique per loan per cycle — used to match ack back to LMS.

Volume considerations

Once daily presentation exceeds ~50,000 debits, batching across multiple files for the same date may be needed per sponsor bank’s limits.

eNACH (Electronic NACH)

eNACH is the API-driven mandate registration alternative to paper:

• Borrower authorises via Aadhaar OTP (most common).
• Or Debit card swipe.
• Or Netbanking.
• Mandate is registered in NPCI’s NPCI-eMandate system within hours.
• Lender receives UMRN.

Once registered, eNACH mandates work identically to paper NACH for presentation purposes.

Vendor implementation: Digio DigiCollect, Razorpay, Cashfree, Setu, Decentro.

UPI AutoPay (newer alternative)

For amounts within UPI AutoPay limits (NPCI-defined; periodically revised), UPI AutoPay provides:

• Real-time mandate registration via UPI app.
• Real-time debit attempts (vs NACH’s T+1).
• Lower bounce rate.

Increasingly used in addition to NACH for backup mandate.

What the platform’s NACH adapter must do

• Presentation file generation per sponsor-bank format.
• Submission via SFTP / API per sponsor bank.
• Ack file processing with bounce-reason code interpretation.
• Re-presentation logic per policy.
• Mandate lifecycle management (registration → active → cancelled).
• UMRN persistence per loan / borrower.
• Sponsor bank failover if multi-sponsor-bank arrangement.

Compliance

• NPCI procedural guidelines govern format and operations.
• RBI Payment System Data Storage — payment data in India.
• DPDP — borrower data in mandate handled with consent.

Related

• 4.8 Mandates and repayments — vendor stack.
• 4.12 Core banking / payouts — sponsor bank.
• 3.K Collections — bounce handling.
• 13.11 Collections backlog.