NACH: bulk debits, credits and recurring payments

NACH is the NPCI system for bulk and recurring payments, and it is the quiet workhorse behind salaries, EMIs, insurance premiums, utility bills, and mutual fund SIPs. NACH handles two kinds of transactions. NACH Credit is used when one debit funds many credits, which is how a company pays salaries to hundreds of employees in one file. NACH Debit is used when many debits fund one credit, which is how a lender collects EMIs from thousands of borrowers on the same date. Instead of processing each payment separately, the bank or corporate uploads a file, NPCI validates it, and the transactions are processed in bulk on the scheduled date. The mandate is the heart of NACH Debit. A customer signs a mandate that authorises a specific biller or lender to debit a specific amount, or an amount up to a defined maximum, from a specific account on specific dates. The mandate can be paper based or electronic. The electronic mandate, known as e-mandate, can be created through net banking, debit card, or Aadhaar based authentication. The mandate has a validity period, a frequency, and a maximum amount, and the customer can revoke it at any time. The mandate lifecycle matters, creation, authentication, activation, amendment, pause, revocation, and expiry, because each state changes what the system is allowed to debit and when. A NACH transaction moves through six clear steps. Step one, the sponsor bank or corporate prepares a file of transactions, with control totals for the count and the value, and uploads it to NPCI. Step two, NPCI validates the file format and the totals, and sends an acknowledgement, rejecting the file if the totals do not match. Step three, NPCI splits the file and sends each destination bank its own inward file for the scheduled presentation date. Step four, each destination bank checks the mandate and the account, debits or credits the customer account, and reports the result. Step five, NPCI settles the net positions between banks through their accounts with the Reserve Bank of India. Step six, NPCI sends back a settlement and return file, and the sponsor bank reconciles every record against the original file. Returns are the normal exception path in NACH, not a rare event. A NACH Debit can return because of insufficient funds, an account that is closed, a mandate that is not registered, an amount above the mandate maximum, or an account that is dormant. Each return carries a reason, and the presenting institution must handle it, inform the customer, and decide whether to retry on the next presentation date. A NACH Credit can also return, for example a salary credit to a closed employee account, and the amount comes back to the employer for correction. Returns arrive in files that the presenting bank must reconcile record by record. A salary file with a wrong total or a missing employee record is a payroll failure, and validation before submission is the most important control. Mandate rejection is a separate exception from a transaction return. A mandate can be rejected at registration because the signature does not match, the account details are wrong, the account does not exist, or the authentication failed. A rejected mandate means no debit can ever be presented against it until the customer corrects the details and registers again. A live mandate can also fail later through dishonour, which is the term used when a presented debit is returned unpaid, most often for insufficient funds. Repeated dishonours can lead the biller to pause the mandate, charge a penalty as per the loan or service agreement, and contact the customer. Design the mandate status screen, the rejection reasons, and the dishonour handling, because a customer who does not know a mandate was rejected will miss an EMI and face a penalty. The scheme rules set the timing an analyst must plan around. NACH runs on presentation and settlement cycles that are slower than UPI or IMPS. A file presented today is processed and settled over the next one or two working days, and failures are reported back in files, not in real time. The value of NACH is reliability and scale for payments that happen on a schedule, not speed. Before NACH, the older ECS system handled the same use cases with regional clearing houses and slower cycles. NACH centralised the system, standardised the file formats, and added the electronic mandate, which made it possible for a lender to collect from customers across the country without paper forms travelling between cities.