---
title: "Tracking emissions over time: How to deal with acquisitions according to the GHG Protocol"
description: Tracking emissions over time
---

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May 21, 2025

# Tracking emissions over time: How to deal with acquisitions according to the GHG Protocol

## How to account for your emissions following Mergers and Acquisitions, and reflect changes in your accounting and digital twin in Cozero.

A meaningful and consistent comparison of emissions over time requires that companies set a performance date with which to compare emissions over time. This performance date is referred to as the *base year emissions*.

For consistent tracking of emissions over time, **the base year emissions may need to be recalculated when companies undergo significant structural changes** such as **acquisitions, divestments, and mergers**.

### **Timing and scope of recalculations:**

When significant structural changes occur during the **middle of the year**, the base year emissions should be **recalculated for the entire year**, rather than only for the remainder of the reporting period after the structural change occurred. Similarly, current year emissions should be recalculated for the entire year to maintain consistency with the base year recalculation. If it is not possible to make a recalculation in the year of the structural change (e.g., due to lack of data for an acquired company), the recalculation may be carried out in the following year. Please see below for more details on three recalculation approaches.

**Important:** Recalculations in the case of acquisition should be done back to the year the acquired company came into existence

### **Recalculation options with a fixed base year:**

#### **All-year option:**

• This approach is recommended by the GHG protocol  
• Recalculate emissions for the entire year, rather than the only period after the acquisition. This means that even if the acquisition happens mid year, the acquired company’s emissions from January to December should be included.  
• Benefits: Avoid recalculation in the following year

#### **Pro-rata option:**

• Recalculate emissions for the portion of the year after the acquisition happened, for example from June to December. For the first year of reporting, only the June to December emissions of the acquired company should be included. This applies to both the current year and base year.  
• In the following year, recalculate to get the full-year picture for the base year and current year

#### **Year-after option:**

• Recalculate only in the report for the year after the structural change. Recalculation will still be required for all past accounting years.  
• Note that the default option **if sufficient data is available**, would be to make the recalculation in the year of the structural change, however when not possible the year-after approach can be used.

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***References:***  
[GHG Protocol Corporate standard ch. 5](https://ghgprotocol.org/sites/default/files/standards/ghg-protocol-revised.pdf) - Tracking Emissions Over Time  
[GHG Protocol Appendix E: Base year recalculation methodologies for structural changes](https://ghgprotocol.org/sites/default/files/standards_supporting/Base%20Year%20Adjustments.pdf)

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