How to keep finance definitions intact through an ERP migration

An ERP migration moves data from one structure to another, but reports depend on what that data means. To keep finance reporting intact, write down and approve the definitions behind your key figures before data moves, map each one to the new chart of accounts and dimensions, and compare results on both systems until the old one retires.

Most migration plans track tables and balances. Few track meaning, and that's where reporting breaks.

Why ERP migrations break reporting

1. A new chart of accounts. Accounts are merged, split or renumbered, and every report that grouped by the old structure shifts.

2. New dimensions. Departments, entities and cost centers are redesigned, so allocations and segment reports move.

3. Logic left behind. Business rules lived in custom fields, reports and spreadsheets that weren't in scope.

4. Historical data. Prior periods are often converted at summary level, so comparisons across the cutover don't line up.

How to migrate definitions, not just data

1. List the figures that must not break, such as revenue, margin, operating expense and the figures in regulatory or board reports.
2. Write and approve a definition for each against the current system.
3. Map each definition to the new chart of accounts and dimensions, and record who made each mapping call.
4. Run both systems in parallel and compare each figure, not just trial balance totals. Agree in advance how large a difference is acceptable.
5. Assign an owner to each definition after go-live, so workarounds don't rebuild the old logic.

Where migrations usually go wrong

IT or the implementation partner owns the migration, and finance owns the meaning. When nobody is accountable for the second part, the first close on the new ERP is where teams discover what was lost.

How Preql helps

Preql's agents map how your current systems define each figure. Business owners approve each mapping, and every decision is versioned with an audit trail and lineage, so the reasoning behind each call survives go-live.

FAQ

How much history should we convert?

Decide per report. Board and regulatory comparisons usually need detail for the prior periods they show. Everything else can often move at summary level.

When should definitions work start?

Before design, when definitions are cheapest to agree and can shape the new chart of accounts.

Does this replace data migration tools?

No. Migration tools move the data. Definitions tell you whether the moved data still means the same thing.