NEC X1 inflation price adjustment factor calculator
Free, no sign-in. Nothing you type is stored or sent anywhere — it's all worked out in your browser.
BCIS indices are a paid subscription. Enter your own licensed index values and the indices/months specified by the Contract Data.
Not legal or tax advice — check your contract. Your contract terms and the facts of your job can change the answer.
How this works
For each row, calculate proportion × (L − B) ÷ B and sum the results to get PAF. The non-adjustable proportion contributes zero but counts towards the required total of 1.00.
Options A and B add two parts: the change in Price for Work Done to Date since the last assessment × the current PAF; and the price adjustment in the last amount due × (current PAF − L) ÷ (1 + L), where L is the previous assessment’s PAF. If either previous-assessment input is blank, the second part is £0.
For Options C and D, the adjustment is the change in Price for Work Done to Date × PAF ÷ (1 + PAF). On these cost-based options Defined Cost is already at current prices. Check the Contract Data and X1 in the contract itself, including amendments.
BCIS indices are a paid subscription. No index feed is supplied here: enter your own licensed values. The Contract Data determines the indices and months to use.
FAQs
Does Civvio provide BCIS values?
No. Enter your own licensed subscription values.
What must the proportions total?
Adjustable proportions plus the non-adjustable share should total 1.00.
Can PAF be negative?
Yes, if latest indices are below base indices.
Does the amount work for Options C and D?
Yes. Select Options C and D: change in PWDD × PAF ÷ (1 + PAF). Defined Cost is already at current prices. Check the Contract Data and X1 in your contract.
Civvio works this out automatically from your contract and site records.
Upload the contract and keep your diary, and Civvio flags the dates, notices and money at risk on every job — for you to review before anything is sent.
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