This guide explains the WeZero expense allocator, which turns procurement spend data into Scope 3 emission estimates. Upload a spreadsheet of supplier spend and the allocator matches each line to an industry using AI, then applies cost-based emission factors to estimate emissions per line. You can review and override any match before accepting the results, and every override is recorded in an audit trail. Completed allocations can be pushed into a reporting year as Scope 3 entries. The guide covers file formats, the review workflow, version history and how allocated figures appear in your results. The expense allocator is available on the Advanced and Managed plans.