★ India · regex

Regex for IFSC Code

The Indian Financial System Code identifies a bank branch for NEFT, RTGS and IMPS. The first four letters are the bank, the fifth character is always 0 (reserved), and the last six identify the branch.

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Try the ifsc code pattern

Read it in plain English (best-effort)

^start of a line
[A-Z]one character from: A–Z
{4}exactly 4 of the previous
0the character '0'
[A-Z0-9]one character from: A–Z, 0–9
{6}exactly 6 of the previous
$end of a line

Test text

One sample per line works well with the m flag on anchored patterns.

Waiting for a pattern

The pattern, piece by piece

/^[A-Z]{4}0[A-Z0-9]{6}$/

Pattern explanation
Part	What it does
`^[A-Z]{4}`	bank code, e.g. SBIN for State Bank of India
`0`	the fifth character is always zero
`[A-Z0-9]{6}$`	branch code

What it accepts and rejects

Every sample below is checked automatically in JavaScript and Python. The tester above is preloaded with all of them, one per line.

Should match
Should match
`SBIN0001234`	✓
`HDFC0000123`	✓
`ICIC0ABC123`	✓
`RBIS0COD001`	✓
`UTIB0000001`	✓
`KKBK0000958`	✓

Should not match
Should not match
`SBIN1001234`	✗
`SBIN000123`	✗
`sbin0001234`	✗
`SBI00001234`	✗
`SBIN00012345`	✗
`SBIN-0001234`	✗

Copy it into your code

RE2-safeNo lookarounds or backreferences, so the same pattern works in Go's RE2 engine and in Rust's regex crate.

Language

const ifscRe = /^[A-Z]{4}0[A-Z0-9]{6}$/;

export function isValidIfsc(value) {
  return ifscRe.test(value.trim());
}

When not to use regex for this

To check an IFSC exists and get the branch address, use RBI's published IFSC list or a lookup API, and refresh it periodically as branches merge.

Questions engineers actually ask

Why is the fifth character always 0?

It's reserved for future use, so every current IFSC has a zero in that position.

Is IFSC case-sensitive?

Codes are uppercase. Uppercase user input before validating.

What is catastrophic backtracking?

Some patterns, usually nested quantifiers like (a+)+, make a backtracking engine try an exponential number of paths on input that almost matches. The tester stops any run after 300ms, so a bad pattern can't freeze your tab. In production, that same pattern can take down a server (a ReDoS attack).