Excel, but it's painful - as any change's through the year make it very hard to compare and contrast actual to budget (e.g. a simple rate change from a supplier vs adding someone to a team, moving different rate people between teams) and quite challenging to do different scenarios (e.g. impact of different inflation levels for different roles / countries). It is possible but requires a lot of discipline and excel expertise from everyone to make it work. I am exploring using a planning & budgeting tool (anaplan, pbcs).
Also the pain you mentioned is exponential with those tools compared to in Excel. You’ll never have perfect budget unless you have a crystal ball and can anticipate everything that will change. Just explain the variance and move on. Forecasting is meant to somewhat solve this issue. Budget become quickly stale, the forecast is budget altered by a few big issues (usually things unknown during the budget). Also usually helpful to replace budget with actual as they become available
