What base year do I enter in CDP (formerly the Carbon Disclosure Project) question 7.5 if I only have two years of complete bills?

Enter the oldest year you have emissions figures for, preferably verified. CDP, formerly the Carbon Disclosure Project, says a first-time measurer should choose the current reporting year. The 7.5 base year need not match your target base year. CDP says to leave a Scope 3 category row blank if you have not calculated it.

What question 7.5 asks for

A table with one row for Scope 1, one for Scope 2 location-based, one for Scope 2 market-based, and one for each of the 15 Scope 3 categories, plus two Other rows. Each row takes a base year end date, the base year emissions in tonnes of carbon dioxide equivalent (CO2e), and methodological details of up to 2,500 characters. The market-based row appears only if you chose to report a market-based figure in question 7.3.

How CDP says to choose the year

• If your company has measured emissions in the past, use the oldest year for which it has emissions information, preferably verified or assured.
• If you are measuring for the first time, choose the current reporting year.
• This base year may be the same as your target base year, but not necessarily.
• If you have not calculated a base year figure for a Scope 3 category, leave that row blank.
• Methodological details should give at least the measurement approach, emission factors, inputs and assumptions, and why you chose them.

Scope 2: both methods in the base year

CDP says the base year inventory should include both a location-based and a market-based Scope 2 total, if applicable and feasible. If your base year was calculated only on the location-based method, recalculate a market-based total where contractual information or residual mix totals exist for that year. If they do not, state in the comment field that the location-based result is used as a proxy because a market-based figure cannot be calculated. If you use one method only, the linked Scope 2 base year answer covers what to add.

One base year for all scopes, with an exception

CDP follows the Greenhouse Gas (GHG) Protocol Scope 3 Standard: companies should use a single base year for Scope 1, Scope 2 and every calculated Scope 3 category. A company with base years already set for Scope 1 and 2 may use a more recent year for Scope 3, for example the first year with complete and reliable Scope 3 data.

Dates and averages

• You enter the end date. CDP assumes the start date is 365 days before it: an end date of 31/12/2023 gives a start of 01/01/2023. For an Indian financial year, an end date of 31/03/2025 gives 01/04/2024 to 31/03/2025 (my reading of the same rule).
• If you use an average of several consecutive years, enter the last date in the period, state the period and say that the figure is an average.
• CDP's guidance allows an average base year (my reading: so it is fine for CDP), but it does not work for a Science Based Targets initiative (SBTi) target, where criterion C13 says the SBTi does not accept multi-year average base years unless sector guidance specifies them. Keep that in mind if the same year must serve both.

Example: oldest complete year is financial year (FY) 2024-25

• Bills on file: April 2024 to March 2026. Oldest complete year: FY 2024-25, so the base year end date is 31/03/2025.
• Scope 1: 42,000 litres of diesel x 2.645 kilograms (kg) per litre = 111,090 kg = 111.09 tonnes.
• Scope 2 location-based: 560,000 kilowatt hours (kWh) x 0.710 kg per kWh = 397,600 kg = 397.6 tonnes. The 0.710 is the Central Electricity Authority (CEA) grid factor for FY 2024-25, the base year here; the current factor is 0.675 for FY 2025-26.
• Scope 3 rows: blank, unless you have calculated a category for that same year.

Litres and kWh are example numbers. Use your own bills and the factor for your own bill year.

What Senseible does here

Senseible reads fuel invoices and electricity bills into monthly records, so the litres, kilowatt hours and months are in one place to copy from. It does not pick your base year or fill in the CDP corporate questionnaire for you, and refrigerant top-ups need your own service records.

• CDP 7.1.3: recalculating a base year
• Scope 2 base year with one method: what to add
• SBTi base year and target years
• CDP 7.3: market-based Scope 2 for an Indian supplier
• Free calculators

Sources: CDP, Full Corporate Questionnaire Module 7 reporting guidance, April 2025 edition, SBTi Corporate Near-Term Criteria, Version 5.3.1, April 2026, C13

Last reviewed 2026-11-05. CDP revises its questionnaire and guidance every year. Check the version your customer sent you before you answer.