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Following this assessment and within one month from the receipt of the contractor’s letter, the contracting authority sends the contractor a final notification including the result of the calculation of the yearly price revision. If applicable, this notification should state the reasons having led to the rejection of the observations put forward by the contractor. 

The notification sent by the contracting authority enters immediately into force and acquires the status of an amendment with full legal effect. 

Should, exceptionally, the contracting authority fail to initiate the procedure as set out above, the contractor may, until 15$^{th}$ October, give formal notice to the contracting authority requiring the latter to send the initial written notification. The contracting authority shall comply with this requirement within 15 calendar days from receipt of the contractor’s letter. Paragraphs 2, 3, 4 and 5 above apply thereafter. 

Should the contracting authority not act as provided for in paragraph 1 above, nor the contractor as provided for in paragraph 6, the yearly price revision does not apply for the relevant yearly period. 

The yearly price revision is calculated using the following formula: 

where: 

Pr = revised price 

## II.19.4. Formula for the yearly price revision 

<img src='content_image/497183.jpg'>

Po = original price in the tender (or, if applicable, in the amendment introducing the price for the service or supplies for the first time) 

Ir = index for the month of May of the year in which the yearly price revision is calculated 

Io = index for the month in which the FWC (or, if applicable, the amendment introducing the price for the service or supplies for the first time) entered into force. 

The quotient of 𝐼𝑟 $_{𝐼𝑜}$ is rounded to the fourth decimal. 

## II.19.5. Indices to be used for the yearly price revision 

For services: the revision is based on the trend in the index “Harmonised Indices of Consumer Prices (HICP all items)”, under “First Published Data (prc_hicp_fp)”, published on Eurostat’s official website. 

For supplies: as regards hardware, complex and other than complex hardware, the revision is based on the trend in the index “Producer prices in industry, domestic market - monthly data [sts_inppd_m]” (PPI NACE C262), published on Eurostat’s official website. 

The precise index to be used is indicated in Article Error! Reference source not found. . 

In case of a change in the base year of an index, the values of “Io”  and “Ir”  are adapted accordingly on the basis of the official figures published by Eurostat using the latest base year. 

Should Eurostat cease to publish any of the indices referred to above, the contracting authority shall - as part of the procedure set out in paragraph II.19.3 above - base the calculation of the revised price on the most similar index which is available, providing reasons for its choice. 

