What are Form Ba-Bs? A practical guide for SMBs

If you run a business in Turkey, you've probably heard "Ba-Bs" from your accountant. These are monthly declaration forms in which you report your purchases (Form Ba) and sales (Form Bs) above a certain amount, together with each counterparty. Their purpose is to let the tax authority do a cross-check: what you say you "bought" should match what the seller says they "sold." In this guide we explain the Ba-Bs forms in plain language.

Note: This content is for general information; the Ba-Bs obligation, thresholds, scope, and dates are set by legislation and can change. For your own situation and the current application, always consult your accountant.

What are Ba-Bs?

Ba and Bs are two separate declaration forms. Form Ba ("declaration of purchases") reports the goods and service purchases you made in a period. Form Bs ("declaration of sales") reports your goods and service sales. Both are prepared in monthly periods, on a per-counterparty basis — that is, you show your transaction volume with each supplier or customer separately. In short, Ba reports "from whom I bought how much" and Bs reports "to whom I sold how much" to the tax authority.

What do you report?

Ba-Bs reports not each transaction individually but the total transaction volume you had with a counterparty within that month — and this volume enters the declaration when it exceeds a certain threshold. So it's not small, scattered transactions; it's the total purchase or sale with the same party above a certain amount. The details of this threshold and scope are set by legislation and are updated from time to time. Confirm the current threshold and what falls in scope with your accountant. What matters is grasping the logic: mutual transactions above a certain size are reported to the authority periodically.

Why do they exist? Cross-audit

The reason Ba-Bs exists is a cross-audit (reconciliation) mechanism. The logic is this: if you bought goods from a supplier, you report this as a "purchase" in your Form Ba; the same supplier also reports what they sold you as a "sale" in their Form Bs. These two declarations are compared at the tax authority — and are expected to be consistent. If one reports a transaction and the other doesn't, this is a signal of a mismatch. This system serves to detect under-declaration and informality; it encourages everyone to report the same transaction the same way.

Who must file?

The Ba-Bs declaration isn't valid for every taxpayer; it generally covers taxpayers subject to a certain bookkeeping method (balance-sheet basis). So your business's type and the method it's subject to determine whether you have this obligation. This distinction matters because a wrong assumption (I didn't have to file but did, or vice versa) can create a problem. Definitely clarify with your accountant whether your business has a Ba-Bs obligation — this is a matter dependent on the personal/business situation and shouldn't be assumed as a general rule.

The scope changing with e-invoice/e-archive

1Monthly Buy/Sell2Above-Threshold Docs3Form Ba / Bs4Monthly Filing5Submit to Tax Office

There's an important development to know here: as e-invoice and e-archive invoice spread, the tax authority already directly has the data of these transactions. So many transactions tied to an electronic document have been excluded from the Ba-Bs declaration — because the authority already gets that information through another channel. So the Ba-Bs obligation has narrowed with e-transformation. This is critical for understanding how the scope has changed. It's useful to review the difference between e-invoice and e-archive and the invoicing guide in this context. Confirm which transactions are still in Ba-Bs scope according to the current situation with your accountant.

Ba-Bs and reconciliation

Form Ba — goods/service PURCHASESForm Bs — goods/service SALESThe tax office's cross-check (reconciliation)Declaration

Ba-Bs is by nature a reconciliation tool: what you report and what the counterparty reports should match. So, for large transactions in scope, reconciling with your counterparties in advance — "the total between us this month is this amount, are we both reporting the same figure?" — prevents encountering a mismatch later. Doing accounts tracking properly is the foundation of this reconciliation; because if you clearly know your purchase-sale total with each counterparty, your declaration is correct too. Scattered account records are the most common source of Ba-Bs mismatches.

When and how is it filed?

Ba-Bs forms are filed in monthly periods, by a certain deadline, and electronically. In practice this declaration is usually prepared and submitted by your accountant based on the records you provide. Your responsibility is to get your purchase-sale documents for that month to your accountant completely and correctly. The filing dates and method are set by legislation and can change; track the current calendar with your accountant. Timely and correct filing matters for both compliance and avoiding possible penalties.

Mismatch and possible penalties

A shortfall, delay, or mismatch with the counterparty in the Ba-Bs declaration can draw the tax authority's attention and lead to administrative sanctions. For example, not filing the declaration at all, filing late, or filing incorrectly/incompletely can create a penalty depending on the conditions. So keeping your records clean and filing on time matters. Penalty conditions and amounts are set by legislation and can change; consult your accountant for your own situation. The goal is to run this process smoothly not out of fear of penalty but with an orderly record discipline.

The Ba-Bs and VAT relationship

Ba-Bs declarations should be consistent with your other declarations, primarily VAT declarations. The authority's cross-check seeks consistency not only within Ba-Bs itself but also between different declarations. For example, a large discrepancy between the sales volume you reported and the amounts in your VAT declaration can be a reason for a query. Special cases like VAT withholding also need to reflect correctly into this holistic picture. All your declarations telling the same truth is essential for both compliance and credibility. Work with your accountant for consistency across declarations.

Preparing for Ba-Bs in bookkeeping

What makes Ba-Bs smooth is actually a good bookkeeping order. If you record your purchase and sale documents in an orderly way and clearly track your transactions with each counterparty, Ba-Bs preparation at period-end stops being a headache. This is one of the basic purposes of bookkeeping: having a clean, complete, and reconciled record in hand when official declarations come. Keeping documents orderly rather than leaving them to the last moment both eases your accountant's work and minimizes possible mismatches. A good record discipline turns Ba-Bs from a burden into a routine transaction.

Common mistakes

• Wrongly assuming the obligation: Assuming whether you must file without asking your accountant creates a problem.
• Not reconciling with the counterparty: If your and the counterparty's figures don't match, a mismatch arises.
• Not knowing the current scope: The scope narrowed with e-invoice/e-archive; don't act on old assumptions.
• Leaving documents to the last moment: A scattered record turns period-end filing into a headache.
• Inconsistency across declarations: Ba-Bs contradicting declarations like VAT can be a reason for a query.
• Late or incomplete filing: Delay and shortfall can create an administrative sanction depending on the conditions.

Getting-started checklist

• 1. Clarify your obligation. Ask your accountant whether you must file Ba-Bs.
• 2. Record purchase-sale documents in an orderly way. Track transaction volume with each counterparty.
• 3. Learn the current scope. Confirm which transactions are out of scope with e-documents.
• 4. Reconcile with counterparties. Make sure the figures match on large transactions.
• 5. Keep consistency across declarations. Don't let Ba-Bs contradict VAT etc.
• 6. File on time. Get the documents to your accountant completely and in time.

Frequently asked questions

Should I file Ba-Bs myself?

In practice, this declaration is usually prepared and submitted by your accountant based on the records you provide. Your real responsibility is to get the purchase-sale documents for that period to your accountant completely and correctly. This division of labor secures both accuracy and compliance with legislation.

If I have e-invoice, don't I need to file Ba-Bs?

As e-invoice/e-archive spread, many transactions tied to an electronic document have been excluded from Ba-Bs scope — because the authority already has that data. However, this doesn't automatically mean "I never file Ba-Bs"; scope and obligation vary by situation. Clarify with your accountant which transactions in your specific situation are still subject to declaration.

What happens if my figures don't match the counterparty's?

When what you report and what the counterparty reports don't match, this can be flagged as a mismatch and lead to a query. So reconciling in advance on large transactions in scope — making sure both parties report the same figure — matters. Scattered account records are the main cause of such mismatches.

What happens if I don't file Ba-Bs?

Not filing the declaration when you're obligated, filing late, or filing incompletely/incorrectly can create an administrative sanction depending on the conditions. So it's important to first clarify your obligation, then file the declarations on time and correctly. Penalty conditions depend on legislation and the situation; consult your accountant.

The Ba-Bs forms are a mechanism that looks complex but whose logic is simple: you report your purchases (Ba) and sales (Bs) above a certain threshold periodically, and the authority cross-checks these against your counterparties'. Even though its scope narrowed with e-transformation, if you're obligated, correct and timely filing matters. The real job on your side is keeping your purchase-sale documents and account records clean; run the technical details and current scope with your accountant. This content is for general information; consult your accountant for your own situation.