Calculate the work increase limit
Enter the contract type and the first contract price to see how close the approved increases are to the limit, whether a new increase would pass it, and the additional bond it needs. No sign-up.
Work increase
Enter amounts at contract prices, excluding VAT. Decreases do not free up room; add up the increases only.
Enter the contract type and the first contract price, or try the sample data.
How the work increase limit is calculated
A work increase made necessary by something unforeseeable can be given to the same contractor up to a share that depends on the contract type. The share applies to the first contract price.
Limit = first contract price × share
Approved increases + new increase ≤ limit
The limit is rounded down to the kuruş, so adding the room shown never passes it. An increase exactly at the limit does not count as passing it.
Rules applied
- 20% on unit price, 10% on lump sum
- Up to 20% of the contract price on unit-price contracts and 10% on turnkey lump-sum ones (General Specification art. 21/1, Law No. 4735 art. 24).
- 40% by presidential decision
- On unit-price contracts and the unit-price part of a mixed one, the share can be raised to 40%, contract by contract (art. 21/2-3).
- Two limits on a mixed contract
- The lump-sum part is limited to 10% of its amount and the unit-price part to 20% (art. 21/3). Each limit applies on its own.
- Conditions
- The added work must stay within the contract's design, and splitting it from the main work must not be technically or economically possible (art. 21/1).
- New-price work
- For a tender announced before 01.09.2025, the amount is brought back to the tender date: divided by the application month's Pn, or with the Domestic PPI ratio where there is no price adjustment. For later tenders, the new unit price is set for the tender month where price adjustment applies and for the approval month where it does not; if the approval comes after the completion date, it is brought back to that date (art. 21/6).
- Over the limit, the contract is wound up
- If the work cannot be finished within these limits, no increase is made and the contract is wound up under the general provisions (art. 21/4).
What this tool does not calculate
It does not compute Pn; where price adjustment applies, you enter the application month's Pn. It does not judge whether the conditions for an increase are met. The completion compensation for work finished below 80% of the contract price has its own tool.
Calculate the completion compensationLegal basis: Public Procurement Contracts Law No. 4735, art. 24; General Specification for Works art. 21; Works Tender Implementing Regulation, provisional art. 34; Works Standard Contract art. 10.2.1. For information only.
About work increases
- Price IndicesDomestic PPI sub-indices and CPI, monthly tables since 2012.
- Price Adjustment CalculatorPrice adjustment with the official formula, from Domestic PPI and CPI.
- Progress Payment Deductions CalculatorThe cover's VAT, every deduction from a) to k) and the net amount paid to the contractor, on one sheet.
- Quantity Takeoff CalculatorRebar, concrete, formwork and excavation takeoffs: a measurement sheet with deductions, exact totals and a copy for Excel.
- Index Change CalculatorHow Domestic PPI and CPI moved since your tender month, with the In/Io ratio.
- Work Experience Update CalculatorWhat a work experience certificate counts for in the tender you enter, with the right Domestic PPI months for its kind.
- Stamp Duty CalculatorThe 9.48 per mille stamp duty on a progress payment, with the yearly cap.
- VAT Withholding CalculatorThe VAT withheld on a progress payment, at the communiqué's rate for the work type.
- Withholding Tax CalculatorWithholding tax on a multi-year construction payment, at the rate for the work type and payment month.
- Performance Bond CalculatorThe performance bond on a bid, with the below-limit 9% rule and additional bonds.
- Minimum Labour CalculatorThe minimum labour to declare for the SGK clearance, the shortfall and its estimated premium.
- Advance Payment CalculatorThe advance, its 30% or one-third cap, the recovery rate and what comes off each progress payment.
- Completion Compensation Calculator5% of the shortfall when work ends below 80%, updated to the acceptance month by Domestic PPI.
- Delay Penalty CalculatorThe delay penalty from the first contract price, daily rate and days late, with the 15% cap.
- Work Duration CalculatorCompletion date from the site handover, days late, final acceptance and payment deadlines.
- Fuel PricesEPDK monthly averages by fuel type, for the fuel coefficient of a price adjustment.
Stop tracking work increases in a spreadsheet
Every work increase is checked against the limit, and its additional bond comes about by itself.