Assumption accounts in Workday Adaptive Planning are purpose-built for storing global constants — such as inflation rates, tax rates, or standard multipliers — that are referenced across multiple formulas and sheets. By design, Assumption accounts allow data entry at the Top Level (Only), meaning a single value is maintained centrally and referenced uniformly throughout the model. This aligns with best practices for model maintainability: rather than hard-coding values into individual formulas, a central Assumption account serves as the single source of truth. When the inflation rate changes, the administrator updates one cell, and all dependent formulas recalculate automatically. This eliminates version drift and ensures consistency across the entire model. Modeled accounts are used for row-based planning; Metric accounts display calculated KPIs but are not editable input stores; Custom accounts have different structural roles. Assumption accounts are foundational in Adaptive Planning's architecture and appear prominently in the Accounts configuration under Model Management. Reference: Workday Adaptive Planning — Accounts Setup, Assumption Account Configuration, Model Management.