MIS Migration and the School Census: The Hidden Data Risk Your School May Not Have Budgeted For

If your school has changed its Management Information System (MIS) at any point since October 2024, this post is for you. It covers a specific and largely invisible risk that we are seeing affect schools following MIS migration — data quality failures in the school census that nobody warned you about, and that can sit undetected until an audit or a funding query forces them into the open.

We are not talking about an obvious system crash or a failed import with an error message. We are talking about data that appears complete on the surface, passes basic validation, and submits without complaint — but is in practice incomplete, incorrectly aligned, or in some cases overwritten with default or placeholder values during the migration process.

Who should read this

Any school that has migrated away from SIMS — or any other MIS — since October 2024 and has since submitted a school census return on the new system. This includes schools that are due to submit the census for the first time on a new platform in autumn 2025 or spring/summer 2026.

Why MIS migration creates a census data risk

When a school migrates from SIMS to a new MIS, the new provider cannot take a direct copy of the SIMS database — SIMS does not permit this. Instead, the migration team works from SIMS-generated reports: structured exports of pupil data, attendance records, SEN information, prior attainment, and so on, which are then uploaded into the new system.

It is at this point that the problem begins. When data is transmitted to the new system via reports rather than a direct database transfer, it passes through a layer of interpretation. Field names do not always match between systems. Report exports may not capture every data point. And critically, where the new MIS already holds a default or system-generated value for a field, the incoming data from the SIMS report may not overwrite it — or it may be the other way around, with a default value silently overwriting the correct migrated data.

The result is a census return that the system accepts without error, but which reflects neither the original SIMS data nor a fully accurate current picture. Some fields are simply absent. Others carry values that were never valid for those pupils. The submission passes. No alarm sounds. But the data is wrong.

What we are seeing in practice

Across the schools we have worked with since October 2024, we have identified four distinct failure patterns:

Failure mode	Likelihood	Impact	What it means in practice
Year group omitted from census — typically Year 11 leavers or post-16 pupils	High	Severe	Entire cohort absent from the census return; pupil characteristics, attendance and outcomes data missing; potential funding and accountability implications
Prior attainment data partially or wholly absent	High	Significant	Affects funding band calculations for secondary and post-16 settings; incorrect banding may go unnoticed until reconciliation
SEN and EHCP records not fully migrated	Medium	Significant	Pupils incorrectly coded as no SEN need; affects per-pupil premium calculations and statutory reporting accuracy
Historical census data not carried into new MIS reports	Medium	Moderate	Continuity break between census years; new MIS reports do not align to prior census submissions; causes reconciliation failures and audit queries

The pattern is inconsistent — which makes it harder to catch. Some migrations succeed entirely. Others fail on one specific field type. Some affect only certain year groups. There is no single error that flags the problem; it has to be found by someone who knows what to look for.

Why it varies

The failure mode depends on which version of SIMS the school was running, how the migration was scoped, which SIMS reports were used as the source, and how the receiving MIS handles conflicts between incoming data and its own default values. Two schools migrating to the same new platform can have entirely different outcomes — and neither may know there is a problem.

What you need to check — and when

If your school changed MIS between October 2024 and the present, you should carry out a structured review covering three points in time:

1. The October 2025 census return

This is your first full census submitted on the new system. It is the one most likely to carry the consequences of any migration data loss. You need to verify:

Total pupil headcount matches your school roll — every year group present and accounted for
Pupil-level data is complete for all pupils: prior attainment, SEN status, free school meal eligibility, ethnicity and language
Year 11 and any post-16 pupils are correctly included — this cohort is most commonly omitted
The data in the census extract matches what is visible in the new MIS — not just what was in SIMS

2. Data continuity from the census into your live MI reports

Once the October 2025 census has been submitted, check that the data submitted has correctly flowed into the current iteration of your MI reports in the new system. This matters because some MIS platforms draw report data from a separate data store that may not be fully synchronised with the census submission.

3. The October 2026 census return

Before the October 2026 census is submitted, run a reconciliation check to confirm that the MI reports your new system generates in autumn 2026 align to the data submitted in the October 2025 census. This is the continuity check — it ensures there is no compounding drift between census years.

Key principle

The data submitted in October 2025 is your baseline. Everything that follows — every MI report, every funding calculation, every census return through 2026 and beyond — needs to be traceable back to that baseline. If the baseline is wrong, the error compounds.

Suggested risk register entry

We recommend that any school in scope for this issue logs the following on its risk register. This provides governance visibility, creates an audit trail, and ensures the review is formally assigned and completed.

Field	Entry
Risk title	School census data integrity — MIS migration data loss
Risk category	Data quality / Compliance / Financial
Date identified	May 2025
Risk owner	Data Manager / Business Manager
Description	Following migration from SIMS to a new MIS since October 2024, there is a risk that census data submitted in October 2025 — and carried forward into subsequent census returns — is incomplete or inaccurate as a result of partial data migration. Known failure modes include omission of year groups (particularly Year 11), incomplete prior attainment data, and absent or mis-coded SEN records. Failure is silent: no error is generated at the point of submission.
Likelihood (pre-review)	High — affects a significant proportion of schools that migrated via SIMS report-based upload
Impact (pre-review)	High — incorrect census data affects pupil premium calculations, funding allocations, statutory accountability reporting and audit compliance
Risk score (pre-review)	High
Mitigating action	Commission a structured census data review covering: (1) verification of October 2025 census against source SIMS data; (2) confirmation that census data has correctly flowed into current MI reports; (3) pre-submission reconciliation check for October 2026 census return
Target completion	Review of October 2025 census: by end of autumn term 2025. Pre-submission check for October 2026: by October 2026
Budget provision	Allow £3,000–£6,000 for specialist review depending on school size and complexity
Residual risk (post-review)	Low — subject to review findings and any corrective resubmission
Review date	Termly until October 2026 census submission confirmed accurate

Budgeting for the review

Schools often ask whether this review can be handled internally. For some schools, yes — if you have an experienced data manager with capacity and familiarity with the census specification. But for most schools, particularly those where the data manager was not in post during the original SIMS migration, an independent specialist review provides the assurance that governance requires.

The cost of a structured review is modest relative to the risk. A funding miscalculation affecting 30 pupils across two census years can represent a far larger sum than the cost of the check that would have caught it.

Activity	Indicative days	Indicative cost
Review of October 2025 census extract against source data	2–3 days	£800–£1,500
Verification that census data has flowed into current MI reports	1–2 days	£400–£900
Pre-submission reconciliation for October 2026 census	1–2 days	£400–£900
Contingency — corrective action if issues identified	1–3 days	£400–£1,500
TOTAL recommended provision	5–10 days	£2,000–£4,800

How Pro 16plus can help

Pro 16plus provides specialist school data support with deep expertise in the school census, MIS systems and the data flows that connect them. Our census data integrity review is a structured, documented service covering:

A pupil-by-pupil reconciliation of your October 2025 census extract against your source MIS data
Verification that every year group is present and complete, with particular attention to Year 11 and any post-16 provision
Field-level checks on prior attainment, SEN, free school meal eligibility and other key census fields
Confirmation that census data has correctly flowed into your current MI reports
A pre-submission check for the October 2026 census to confirm continuity with the 2025 baseline
A written report suitable for your governing body, risk register and any future audit

We work with schools of all phases and sizes, and we understand the pressures facing data managers and business managers. If you are unsure whether your school is affected, the first conversation is always free.

Get in touch

Contact Pro 16plus to discuss a census data integrity review for your school. Email: p16plus@outlook.com. We will respond within one working day.

About Pro 16plus

Pro 16plus is a specialist school data consultancy providing expert support on the school census, MIS systems, data quality and compliance. We work with primary, secondary and all-through schools across England, supporting data managers, business managers and senior leaders to get the most from their data and to manage the risks that come with it.

pro16plus.co.uk | p16plus@outlook.com