Introduction
Price difference in Turkish public procurement contracts is one of the most important legal and financial issues for contractors, suppliers, service providers and foreign companies doing business with Turkish public authorities. In a market affected by inflation, exchange rate movements, fuel costs, labour expenses, construction material prices and supply-chain fluctuations, the existence or absence of a price difference clause may determine whether a public contract remains commercially sustainable.
In Turkish procurement practice, price difference is known as “fiyat farkı.” It is not a general right to renegotiate the contract price whenever costs increase. It is a statutory and contractual mechanism that operates only under the applicable legislation, tender documents and contract provisions. The Public Procurement Authority’s legislation page lists Law No. 4735 on Public Procurement Contracts and the current Price Difference Principles among the core legal sources governing public procurement contracts and price difference practice.
The main legal framework is Public Procurement Contracts Law No. 4735, especially Article 8, together with separate price difference principles for goods procurement, service procurement and construction works. In practice, the administrative specification, draft contract, price difference principles, progress payment rules, delivery schedule, work program, time extension decisions and EKAP records must be reviewed together. Public Procurement Authority sources expressly state that the price difference principles for goods and service procurement are based on Article 8 of Law No. 4735.
What Is Price Difference in Turkish Public Procurement?
Price difference is an adjustment mechanism used to calculate an additional payment to the contractor or, in some cases, a deduction from payments, due to changes in legally defined cost indices or input prices after the contract is signed. It is not the same as contractual amendment, additional work payment, compensation, damages or force majeure relief.
In goods procurement, the official price difference principles define price difference as the amount to be paid or deducted under the relevant principles for goods delivered in accordance with the delivery schedule in unit price contracts, or according to total delivery percentages in lump-sum contracts. Those principles also state that price difference payments or deductions do not affect the original contract price.
This distinction is essential. Price difference may increase or decrease the amount paid under a progress payment, but it does not automatically change the original contract price, the performance bond basis, the contract type or the scope of work. It is a calculation mechanism attached to performance under the contract.
Legal Basis Under Law No. 4735
Price difference in Turkish public procurement contracts is primarily governed by Article 8 of Law No. 4735 and the price difference principles issued for different procurement types. The Public Procurement Authority’s legislation page identifies the current price difference principles as a distinct category under procurement legislation and lists current principles, previous versions, amendment principles and temporary price difference regimes.
The legal structure is important because public procurement contracts are not ordinary private contracts. Under Law No. 4735, public procurement contracts must be prepared and implemented according to the tender documents and applicable public procurement rules. The price difference mechanism must therefore be examined at the tender stage, not only after contract signing.
In practical terms, a contractor should never assume that it can demand price difference merely because costs increased. The contractor must first determine whether the tender documents and contract contain price difference provisions, whether the relevant procurement type allows or requires price difference, and which formula, indices and coefficients apply.
Price Difference Must Be Included in Tender Documents and Contracts
One of the core rules is that price difference must generally be regulated in the administrative specification and contract. The price difference principles for goods procurement state that, for price difference to apply in goods procurement under Law No. 4734, the administrative specification and contract must state that price difference will be calculated under the relevant principles.
The service procurement price difference principles similarly state that, for contracting authorities to calculate price difference in service procurements under Law No. 4734, the provisions in those principles must be included in the administrative specifications and contracts.
This means that bidders must review the tender documents before pricing their offers. If price difference is not included, or if the formula is incomplete, unclear or unlawful, the bidder should evaluate whether a complaint must be filed before the tender deadline. Waiting until performance becomes unprofitable may be too late.
No Post-Contract Change of Price Difference Rules
Another crucial rule is that the price difference provisions in the contract cannot be freely changed after signing. The goods procurement price difference principles expressly state that the principles and procedures regarding price difference in contracts cannot be changed after the contract is signed.
This rule reflects a broader principle of public procurement contracts: the tender is conducted on the basis of fixed documents known to all bidders. If the administration and contractor could change price difference rules after award, equal treatment and competition could be undermined. Other bidders may have priced differently if they had known that a more favourable price difference regime would later be applied.
Therefore, price difference must be treated as a pre-bid risk issue. Bidders should ask: Is price difference available? Which inputs are covered? Which indices apply? Are the coefficients realistic? Does the formula cover labour, fuel, materials, exchange-rate exposure or only selected inputs? Is the contract long enough to require mandatory price difference under current rules?
Price Difference in Goods Procurement Contracts
Goods procurement price difference rules apply to public contracts for the purchase of goods under Law No. 4734 and Law No. 4735 where the relevant conditions are met. The goods procurement principles state that they determine the procedures and principles for calculating price difference in goods procurement contracts concluded under Law No. 4735 by administrations subject to Law No. 4734.
Goods procurement may include medical devices, medicines, fuel, food products, machinery, vehicles, equipment, software licences, laboratory systems, furniture, construction materials and other public-sector supplies. Price difference may be especially important where goods are delivered over time rather than immediately.
A 2022 Public Procurement Authority announcement stated that, for goods procurement tenders announced on or after 28 March 2022, price difference became possible for the part exceeding 180 calendar days in certain goods procurements other than electricity, natural gas, petroleum products, LPG and medicines, where the contract duration exceeds 180 calendar days. The same announcement also noted specific rules for LNG purchases and EPDK-based pricing.
For suppliers, the key point is that goods procurement price difference depends heavily on the contract duration, the type of goods, tender documents and applicable price difference principles. A supplier importing products or relying on foreign currency inputs should not assume that exchange-rate increases will automatically be compensated through price difference.
Price Difference in Service Procurement Contracts
Service procurement contracts may include cleaning, private security, catering, personnel transportation, vehicle rental, facility management, software support, maintenance, call centre services, technical operation, logistics and similar services. In many service contracts, labour, fuel, food inputs, equipment and operational costs may change significantly during performance.
The Public Procurement Authority’s service procurement price difference principles state that the principles determine the procedures for price difference calculations in service procurement contracts concluded under Law No. 4735. They also provide that the relevant provisions must be included in the administrative specification and contract for price difference to be calculated.
A major 2022 amendment announcement stated that price difference calculation became mandatory in service procurement contracts with a duration exceeding 365 calendar days. It also stated that, where price difference is included in tender documents, the weight coefficients of inputs and the sub-indices to be used must be determined in the tender documents. For meal services with materials, the announcement specified that relevant food product sub-indices published by TÜİK must be used for raw food inputs where price difference is provided.
This is particularly important for labour-intensive service providers. A bidder must calculate whether the price difference formula adequately covers expected labour, fuel, food or material cost increases. If the coefficients are unrealistic or missing, the bid may become commercially risky.
Price Difference in Construction Contracts
Construction works are one of the most sensitive areas for price difference. Public construction contracts may last months or years and may involve cement, iron, steel, asphalt, fuel, machinery, labour, subcontractors, imported materials and energy costs. Without an appropriate price difference mechanism, a construction contractor may face severe cost escalation.
A 2022 Public Procurement Authority announcement stated that price difference calculation became mandatory in construction works with a contract duration exceeding 365 calendar days. It also stated that, where the administration includes price difference in the tender documents, the weight coefficients of inputs and the sub-indices to be used must be determined in those documents, and that EPDK-published prices are used for fuel input in price difference calculations.
Construction contractors should review the price difference formula together with the work program, unit price schedule, technical specification, delivery dates, time extension clauses and progress payment rules. In construction contracts, price difference is often tied to the portion of work performed within a specific period. If the work program changes, price difference calculations may also be affected.
2025 Amendments: New Sub-Indices and Revised Work Programs
Price difference rules are not static. The Public Procurement Authority announced that legislation amending the price difference principles was published in the Official Gazette dated 30 July 2025 and numbered 32971, and that those amendments apply to tenders announced or notified after 1 September 2025 and their related contracts.
According to the same announcement, the 2025 amendments allowed the use of 24 new sub-indices published by TÜİK in price difference calculations for goods procurement, service procurement and construction contracts. The announcement also clarified which unit price should be used for price difference where a new unit price is calculated for construction work items without a contract unit price.
The 2025 amendments also addressed situations where multiple progress payments are prepared within the same month and the relevant indices for that period are not yet available. In that case, the announcement states that previous current indices may be used initially and that corrections may be made in later progress payments once the relevant indices for the application month are published.
Another important 2025 clarification concerns time extensions. The Authority announced that the amendments clarified how price difference should be calculated according to revised work programs prepared after time extensions in service procurement and construction contracts.
Price Difference and Revised Work Programs
Revised work programs are especially important in construction and long-term service contracts. If the contractor receives a time extension due to force majeure, administrative delay, project change or another legally accepted reason, the timing of performance changes. Since price difference is often linked to the period in which performance occurs, the revised program may affect the calculation.
The 2025 amendments expressly clarified price difference calculation according to revised work programs after time extensions in service and construction contracts.
For contractors, this means that a time extension request should not be viewed only as a delay issue. It may also affect price difference rights. The contractor should ensure that the revised work program is prepared correctly, approved properly and reflected in progress payment calculations.
For administrations, the same issue creates a documentation obligation. If the revised work program is unclear, incomplete or inconsistent with the time extension decision, later price difference disputes may arise.
Price Difference and Progress Payments
In many public procurement contracts, price difference is calculated together with progress payments. The timing of performance, the relevant indices, the work items performed and the applicable formula all matter.
The 2025 Public Procurement Authority announcement specifically addressed the case where more than one progress payment is issued within a single month and the relevant indices are not yet known. The announcement states that the calculation may initially be made using previous current indices and then corrected in later progress payments when the indices for the application month become available.
This is important in practice because contractors often dispute whether the correct index month was used, whether the performed work was assigned to the correct period, whether corrections were made, and whether deductions or additions were calculated accurately.
Contractors should review every progress payment statement carefully. If a price difference calculation is missing or incorrect, the contractor should object in writing within the procedural framework applicable to the contract.
Price Difference and Foreign Currency Contracts
Price difference should not be confused with foreign exchange adjustment. The goods procurement price difference principles state that those principles do not apply to works where the price is paid in foreign currency or in Turkish lira equivalent with separate exchange-rate difference calculations.
This rule is extremely important for foreign companies, importers and suppliers relying on foreign currency inputs. If a contract is denominated in foreign currency or includes a separate exchange-rate mechanism, the ordinary price difference principles may not apply in the same way. Conversely, if the contract is in Turkish lira and does not include sufficient price difference protection, the contractor may bear exchange-rate risk.
Foreign bidders should therefore review the contract currency, payment provisions, price difference clause, import costs, customs expenses, currency exposure and guarantee currency together before bidding.
Price Difference and Additional Performance Bond
Price difference may also affect guarantee obligations indirectly. Under Turkish public procurement contract practice, additional performance bond may become relevant where price difference increases the contract-related payment base under applicable rules. While price difference does not automatically amend the original contract price in the same way as a contract amendment, public procurement contracts may require additional guarantees in certain circumstances.
Contractors should therefore review the performance bond and additional performance bond clauses together with price difference rules. In long-term construction or service contracts, price difference, additional guarantee, advance payment, progress payment and final account rules may interact.
The Public Procurement Authority’s legislation page lists price difference principles and contract-stage instruments under the public procurement framework, showing that these issues are treated as part of the broader contract administration system.
Price Difference, Force Majeure and Time Extension
Price difference and force majeure are different legal mechanisms. Force majeure may justify time extension or other contract consequences where legal requirements are met. Price difference adjusts payment according to the formula and indices in the tender documents and applicable principles.
A contractor should not assume that force majeure automatically creates a broader price difference right. If a time extension is granted, price difference may need to be recalculated according to the revised work program where the applicable rules provide for it. The 2025 amendments specifically clarified price difference calculation after time extensions for service and construction contracts.
This is why contractors should document both issues separately. A time extension request should explain the delay event and its effect on the work program. A price difference claim should identify the applicable formula, index, coefficient, performed work and progress payment period.
Price Difference and Tender Strategy
For bidders, price difference is a pricing issue before it becomes a dispute issue. A company should not bid without understanding whether the contract includes price difference and how it works.
A supplier should ask whether the delivery period exceeds relevant thresholds, whether the goods are covered by price difference principles and whether foreign currency exposure is protected. A service provider should examine labour, fuel, food, equipment and other input coefficients. A construction contractor should analyse material indices, fuel rules, work program, unit prices and time extension consequences.
If price difference is mandatory under current legislation but missing from the tender documents, the bidder should consider filing a complaint before the tender deadline. If price difference is optional but included in an unclear or defective way, the bidder may need clarification or objection. If no price difference is available, the bidder must price the risk.
Legal Remedies for Price Difference Disputes
Price difference disputes may arise at different stages.
Before bid submission, the dispute may concern unlawful or missing tender document provisions. In that case, candidates, tenderers or potential tenderers may need to file a complaint before the contracting authority and, if necessary, an appeal complaint before the Public Procurement Authority under Law No. 4734. Tender document objections are deadline-sensitive.
During contract performance, disputes may concern progress payment calculations, wrong indices, wrong coefficient application, failure to apply revised work program, refusal to pay price difference, unlawful deductions or final account disagreements. These disputes may require written objections, administrative applications, contractual dispute mechanisms and, where necessary, litigation.
The correct remedy depends on the stage of the dispute. A bidder cannot usually wait until contract performance to challenge a price difference clause that was clearly visible in the tender documents. Conversely, a contractor challenging a progress payment calculation must focus on contract performance records and calculation evidence.
Practical Checklist for Bidders
Before submitting a bid in a Turkish public tender, companies should use the following price difference checklist:
Review whether price difference is included in the administrative specification and draft contract.
Check whether price difference is mandatory because of contract duration or procurement type.
Identify which price difference principles apply: goods, services or construction.
Review input coefficients and sub-indices.
Check whether fuel, labour, materials, food inputs or imported components are covered.
Verify whether the contract is in Turkish lira or foreign currency.
Assess whether the formula protects the main cost drivers.
Check whether the delivery schedule or work program is realistic.
Evaluate the risk of time extensions and revised work programs.
Calculate expected price difference under several inflation and cost scenarios.
Object before the tender deadline if the tender documents are unlawful, incomplete or contradictory.
Practical Checklist for Contractors During Performance
During contract performance, contractors should monitor price difference systematically:
Preserve the signed contract, administrative specification and price difference clause.
Keep the approved work program and all revised work programs.
Record actual performance dates.
Track progress payment periods.
Check which index month is applied.
Verify that the correct TÜİK or EPDK data is used where applicable.
Review coefficients and formula calculations.
Object in writing to incorrect progress payment calculations.
Document time extension decisions and their effect on price difference.
Preserve all correspondence, progress payment statements and final account records.
This documentation is essential. Price difference disputes are usually calculation-heavy, and the contractor must be able to show where the administration’s calculation is wrong.
Common Mistakes by Contractors
The first common mistake is assuming that price difference is automatic. It depends on the applicable law, tender documents, contract provisions and procurement type.
The second mistake is ignoring tender document review. If the price difference formula is defective, the bidder should act before the tender.
The third mistake is relying on general inflation arguments. Price difference is calculated according to legal formulas, not general fairness.
The fourth mistake is failing to track indices and progress payment periods.
The fifth mistake is not objecting to incorrect progress payments in writing.
The sixth mistake is confusing foreign exchange loss with price difference.
The seventh mistake is failing to update the work program after time extension.
The eighth mistake is underestimating the impact of coefficients and sub-indices.
Common Mistakes by Contracting Authorities
Contracting authorities also make recurring mistakes.
The first is failing to include mandatory price difference provisions in long-term service or construction contracts.
The second is including price difference but failing to determine input weight coefficients or sub-indices clearly.
The third is using the wrong index month.
The fourth is failing to correct progress payments when indices become available later.
The fifth is ignoring revised work programs after time extension.
The sixth is treating price difference as discretionary even where the contract and applicable principles require calculation.
The seventh is changing price difference rules after contract signing, despite the prohibition on post-contract changes to price difference procedures.
These mistakes may lead to complaints, contract disputes, payment claims and litigation.
Special Considerations for Foreign Companies
Foreign companies should pay special attention to price difference in Turkish public procurement contracts. Many foreign bidders rely on imported goods, foreign currency financing, international suppliers or overseas manufacturing. Turkish public contracts may not fully protect these cost risks.
A foreign company should review whether the tender price is in Turkish lira, whether price difference is available, whether foreign currency contracts are excluded from ordinary price difference principles, whether import-related costs are covered and whether customs, logistics and exchange-rate risk remain with the contractor.
Foreign bidders should also consider the practical timing of payments. Even where price difference is available, payment may occur through progress payment mechanisms after performance. Cash-flow planning should include possible delays, index publication timing and corrections in later progress payments.
Frequently Asked Questions
What is price difference in Turkish public procurement contracts?
Price difference is a statutory and contractual calculation mechanism that may result in additional payment to, or deduction from, the contractor according to legally defined formulas, indices and contract provisions.
Is price difference automatically paid in every public procurement contract?
No. Price difference generally depends on the applicable price difference principles, tender documents, administrative specification and contract. In some long-term service and construction contracts, current rules may require price difference, but the tender documents must still be reviewed carefully.
Can price difference rules be changed after contract signing?
The goods procurement price difference principles state that the procedures and principles concerning price difference in contracts cannot be changed after the contract is signed.
Is price difference mandatory in long-term service contracts?
A Public Procurement Authority announcement stated that price difference calculation became mandatory in service procurement contracts with a duration exceeding 365 calendar days.
Is price difference mandatory in long-term construction contracts?
The same Public Procurement Authority announcement stated that price difference calculation became mandatory in construction works with a contract duration exceeding 365 calendar days.
What changed in 2025?
The 2025 amendments allowed the use of 24 new TÜİK sub-indices, clarified price difference for construction work items without unit prices, addressed multiple progress payments in the same month, and clarified calculations according to revised work programs after time extensions in service and construction contracts.
Does price difference apply to foreign currency contracts?
The goods procurement price difference principles state that those principles do not apply to works paid in foreign currency or Turkish lira equivalent where exchange-rate differences are calculated separately.
Conclusion
Price difference in Turkish public procurement contracts is a decisive legal and financial mechanism. It can protect contractors against certain cost increases, but only within the limits of Law No. 4735, the applicable price difference principles, tender documents and contract provisions.
For bidders, the most important stage is before bid submission. The administrative specification, draft contract, price difference formula, coefficients, indices, procurement type, contract duration, currency, delivery schedule and work program must be reviewed carefully. If price difference is mandatory but missing, or if the formula is defective, the bidder should consider timely legal remedies before the tender deadline.
For contractors, price difference must be managed during performance. Progress payments, index months, revised work programs, time extension decisions, TÜİK and EPDK data, and final account calculations should be documented and checked. Written objections should be submitted promptly where calculations are incorrect.
For foreign companies, price difference analysis is especially important because foreign exchange exposure, imported inputs and international supply chains may not be fully covered by Turkish price difference rules.
In Turkish public procurement, price difference is not a general fairness adjustment. It is a strict legal calculation mechanism. Companies that understand it before bidding can price risk correctly, protect their contractual rights and avoid major disputes during performance.
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