Bulgaria IBAN Format (BG) — Structure, Length & Validator

The Bulgarian IBAN is a 22-character format with a distinctive alphanumeric BBAN, the bank identifier uses four uppercase letters, making Bulgarian IBANs immediately recognisable alongside the alphabetic Irish and Latvian formats. Bulgaria adopted the euro on 1 January 2025, and all BG IBANs now operate natively within the SEPA euro payment system.

Bulgarian IBAN at a Glance

• Country code: BG
• Total length: 22 characters (always)
• Format: BGkk bbbb cccc tt aaaaaaaa
• BBAN length: 18 characters (4 letters + 14 digits)
• Currency: Euro (EUR), Bulgaria joined the eurozone on 1 January 2025
• SEPA member: Yes

Bulgarian IBAN Structure Explained

A Bulgarian IBAN has five BBAN components within its 22-character body:

1. Country Code, BG (2 characters)

The ISO 3166-1 alpha-2 code for Bulgaria. Every Bulgarian IBAN begins with BG.

2. Check Digits, kk (2 digits)

Two decimal digits calculated using the MOD-97 algorithm. They protect against transcription errors across the full 22-character IBAN.

3. Bank Code, bbbb (4 uppercase letters)

A 4-character alphabetic bank identifier. This is derived from the bank's BIC code. Common Bulgarian bank codes:

• BNBG, Bulgarian National Bank (Bulgarska Narodna Banka)
• UBBS, United Bulgarian Bank (UBB)
• BPBI, Postbank (Eurobank Bulgaria)
• FINV, First Investment Bank (Fibank)
• UNCR, UniCredit Bulbank
• STSA, DSK Bank (part of OTP Group)
• CECB, Central Cooperative Bank

The presence of four uppercase letters in the BBAN is a key distinguishing feature of Bulgarian IBANs and means they cannot be fully numeric. Note that Raiffeisenbank Bulgaria (RZBB) merged into United Bulgarian Bank in 2023, and RZBB IBANs stopped working in November 2024; payments to old RZBB IBANs should be redirected to the beneficiary's current UBB account.

4. Branch Code, cccc (4 digits)

A 4-digit code identifying the specific branch within the bank. Different branches of the same bank carry different codes.

5. Account Type, tt (2 digits)

A 2-digit code indicating the account type (e.g., current account, savings account, loan account). This is part of Bulgaria's domestic account classification system.

6. Account Number, aaaaaaaa (8 digits)

The 8-digit individual account number at the identified branch.

Real Bulgarian IBAN Example

BG80 BNBG 9661 1020 3456 78

• Country: BG
• Check digits: 80
• Bank code: BNBG (Bulgarian National Bank)
• Branch code: 9661
• Account type: 10
• Account number: 20345678

Electronic format: BG80BNBG96611020345678

How Bulgarian IBAN Validation Works

1. Country code: First two characters must be BG.
2. Length: Exactly 22 characters after removing spaces.
3. Character types: Positions 3–4 are digits; positions 5–8 are uppercase letters; positions 9–22 are digits. A Bulgarian IBAN that contains letters outside positions 5–8 is structurally invalid.
4. MOD-97: Rearrange, convert letters to numbers (A=10…Z=35), compute modulo 97. Result must equal 1.

The ibanchecker.cash validator runs all checks and decodes the bank code, branch, account type, and account number for any Bulgarian IBAN.

Bulgaria's Euro Adoption and SEPA

Bulgaria adopted the euro on 1 January 2025, ending the Bulgarian lev (BGN) era. All Bulgarian bank accounts migrated to euro denomination on that date. Existing BG IBANs were retained, the account number structure did not change. Bulgaria is a full SEPA member, so SEPA Credit Transfers and Direct Debits apply. For transfers outside SEPA, the BIC/SWIFT code is required. Look up any Bulgarian bank's BIC with the ibanchecker.cash SWIFT directory.

Common Bulgarian IBAN Mistakes

Lowercase Bank Code

The 4-letter bank identifier must be uppercase (BNBG, not bnbg). Always uppercase the full IBAN before validation or API transmission.

Confusing with German or Irish IBANs

Bulgarian and Irish IBANs are both 22 characters and both contain 4 letters in the BBAN. The distinguishing feature is position: Irish letters appear at BBAN positions 1–4; Bulgarian letters also appear at BBAN positions 1–4 but are followed by an all-numeric 14-digit tail, same position, same length, different country code.

Validating Bulgarian IBANs in Bulk

Finance teams working with Bulgarian vendors or employees can validate multiple IBANs at once using the ibanchecker.cash bulk checker. Upload a CSV with up to 100 IBANs and get instant results, bank name, BIC, and any structural errors flagged per row.

Sources & References

• SWIFT IBAN Registry — Official IBAN country format specifications
• ISO 13616 — IBAN international standard
• Bulgarian National Bank (BNB) — Central bank and payment system oversight
• EPC SEPA Participants — SEPA scheme participants register
• ECB TARGET2 — Eurozone payment system information

Last updated: June 2026