An index is used with January 2021 as the base month to show trends in the retail prices for electricity and gas. The index values are calculated by dividing the price modelled by the Bundesnetzagentur of each month by the price of the base month and multiplying by 100.

The charts also include inflation-adjusted index values to precisely show the actual changes in consumer prices for electricity and gas. The adjustment for inflation is based on the consumer price index for Germany, which is published monthly by the Federal Statistical Office.

The modelled gas price for new customers is made up of surcharges, taxes, network tariffs and fees, distribution costs and margin, and procurement costs. The individual components of the retail price are calculated as follows:

• Information on surcharges, taxes, network tariffs and fees is gathered as part of annual monitoring and assumed to be constant. Changes within the course of the year are reflected immediately. Turnover tax is calculated separately on a monthly basis and added to this price component.
• Distribution costs and margin are gathered as part of annual monitoring and assumed to be constant for the year.
• Procurement costs for new customers are calculated on a monthly basis using the procurement strategy reported by electricity and gas suppliers for annual monitoring. To do this, the respective average prices of the electricity and gas products (day-ahead, monthly products, quarterly products, 1-year futures, 2-year futures and 3-year futures) are weighted with these products' average shares of total procurement.

To determine the prices for existing customers, a rolling average of the modelled new customer prices from the previous months is used. The number of previous months used is based on responses in the annual monitoring survey on household customers about how long household customers remain in their energy supplier's contract.