What is e-Defter?
e-Defter is Turkey’s mandatory electronic accounting ledger system, administered by the Gelir İdaresi Başkanlığı (GİB). It replaces traditional paper ledgers (Yevmiye Defteri, Defter-i Kebir, Envanter Defteri) with cryptographically signed XBRL-GL format files that companies generate, sign, and submit monthly. The framework is anchored in 213 sayılı Vergi Usul Kanunu (VUK) and General Communiqué No. 1 on e-Defter (2011, as amended).
Mandatory scope
- All companies subject to e-Fatura mandate are also required to maintain e-Defter.
- Annual gross revenue threshold: set by GİB and lowered periodically (recent rounds brought medium-sized businesses into scope).
- Sectoral mandates: certain industries (e-commerce, hosting, accommodation platforms) face mandatory adoption regardless of revenue.
- e-Defter Saklama Hizmeti: qualified electronic ledger archive providers (GİB-authorised) store XBRL files for the legally required retention period.
Operational mechanics
- Monthly cycle: ledger XBRL files generated for the month, stamped with Mali Mühür (qualified electronic seal) or Nitelikli Elektronik İmza, and the resulting berat is uploaded to GİB.
- Berat (excerpt): a summary hash of the ledger that proves integrity; the berat is what GİB receives, while the full ledger is held by the company or saklama provider.
- Filing deadlines: berat must be uploaded by the end of the third month following the ledger period (with sub-period flexibility).
Compliance landscape and integrations
In Turkish accounting practice, ERP systems such as Logo, Mikro, Netsis, Eta and SAP offer e-Defter modules. Most SMEs work through a GİB-authorised private integrator (Özel Entegratör), because building in-house e-Defter infrastructure requires significant investment. Late or defective berat uploads expose the taxpayer to penalties under the Tax Procedure Law (VUK).
Do: integrate via an established Özel Entegratör; reconcile monthly ledger against KDV-1 and Muhtasar declarations; archive XBRL files for the 10-year retention period under TTK Art. 82 (VUK Art. 253 itself requires five years).
Don’t: miss the berat upload deadline: fines compound monthly and prior-period corrections require explanation submissions.
Sources. Tax Procedure Law No. 213. Statute links open the official consolidated Turkish texts on mevzuat.gov.tr.