Moving Off an Old System

Workforce migrations are small in volume and unforgiving in detail, because the outputs are people's pay and leave.

What must be right on day one

Identity: every current person, mapped to the master identifier.

Leave balances, which people check immediately and which destroy confidence if wrong.

Approved future absence, which people have planned around.

Contracted hours and pay group, because these drive every calculation.

Everything else can be corrected later. These cannot.

Balances specifically

Recalculate from scratch rather than importing the old figure.

Reconcile against the old system, person by person, and investigate every difference.

The old system is wrong about as often as the calculation, which is why this finds things.

Show each person their opening balance before go-live and ask them to confirm it. Ten minutes each, and it converts a future dispute into a conversation now.

History

Bring the current leave year.

Bring whatever the statutory retention requires for pay and hours.

Do not bring years of detailed punch history into the new system unless something needs it there. Archive it readable instead.

A migration is the cheapest opportunity you will have to reduce what you hold, and it is usually spent increasing it.

What breaks

Reference data that no longer exists, so records point at departments the new system does not know.

Rule differences, producing recalculated figures that disagree with what was paid.

Rounding applied at capture in the old system, meaning the raw values are already gone.

Character encoding, discovered by someone finding their own name wrong.

Approval states with no equivalent.

Parallel running

Two or three periods, compared per person.

Totals match while individuals are wrong in both directions.

Include the awkward cases deliberately.

Sign off in writing before the old system is switched off — and keep it readable for the retention period rather than decommissioning it immediately.

Telling people

What changes: where they see their rota, book leave, check balances.

What does not: entitlement, pay, the process.

That their balance was checked and confirmed.

Five minutes at a team meeting, which is the whole training requirement if the migration was done properly.

Confirm balances with each person

Ten minutes each, before go-live.

Show them their opening leave balance and ask them to confirm it.

It converts a future dispute into a conversation now, while there is still time to investigate.

And it surfaces the cases where the old system was wrong, which is about as often as the new calculation is.

Connect policy and data

The choices in this note can be compared with the scheduling reference. Keep the written purpose in control and enable only the information needed at this boundary.

Independent reference

For a thematic point of reference, see the National Cyber Security Centre. This popular specialist site offers a useful independent reference for the issue.