A regulatory submission is found to be wrong. You must produce an amended figure and explain the difference. What must the pipeline have supported?

What the interviewer is testing

Whether you know how a regulatory reporting pipeline differs from analytics, and whether those properties were designed in.

What is required now

Reproduce the original figure exactly, which means the input data as it stood at the reporting moment, plus the code and configuration version that produced it. If the pipeline reads live tables and the transformations have since changed, the original number cannot be regenerated and you cannot explain the difference.

Trace the figure to source records through every transformation, because the regulator will ask what changed and why, and an answer assembled by hand takes weeks.

Produce the amended figure with the same rigour, plus a documented explanation of the cause and the delta.

The properties the pipeline must have had

Point-in-time immutable snapshots of inputs, retained for the regulatory period — not a live read of source tables.

Versioned transformations, so the exact logic that produced any prior submission is recoverable, with the version recorded alongside the submission.

Column-level lineage from submitted figure back to source records.

Controls and sign-off: reconciliation against source systems, variance checks against prior periods, and a recorded human attestation, since a person is accountable.

Explicit restatement support: the ability to produce an amended submission with a clear record of what changed, rather than overwriting.

The architectural recommendation

Separate regulatory reporting from the general analytics estate, even at the cost of duplication. Sharing transformation logic with dashboards means every optimisation someone makes for a chart is a change to a regulated calculation — and the change control that implies is not what a BI team signed up for.

What a strong answer adds

The forward-looking control: a four-eyes review and versioned release process for any change to a regulatory calculation, with the same evidence standards as production code. Most restatements originate in an ungoverned change to a shared transformation, and separating the estate is what prevents recurrence.

Common weak answers

Recomputing with current data and current code, which produces a third number and no explanation. Treating lineage as a documentation exercise.