Anyone searching for "HR system migration" has usually already made the decision. The question now is what's waiting for you. This page describes that without marketing language: which data moves, in what form, who takes which step, and where things go wrong in practice.
One number to start with, because it puts a finger exactly on the sore spot. In the 27th HR Systems Survey report from Sapient Insights Group - 3,318 organisations, fieldwork May-June 2024 - more than a quarter of organisations missed their implementation expectations, and 23% missed their adoption expectations. At the same time, only 7% set aside the recommended 20% of the project budget for change management and support, even though 91% say they do change management (Sapient Insights Group, 2024).
Put those together and you get the core of this article: HR migrations rarely fail on the import. They fail on what's not right after the import.
How long does a migration to a new HR system take?
Two numbers, and the gap between them is where most project plans go wrong.
The transfer itself is fast: Peepel is operational within one day. The cleaner your starting point, the fewer exceptions and mismatched counters you still need to review in the data check.
Go-live falls on the 1st of a payroll month. That's not a technical limitation, it's a process agreement. In practice it means the calendar sets your start date: sign halfway through September, and your first payroll run through Peepel happens in October.
Key takeaway: Peepel is operational within one day. The wait for the first payroll run is set by the payroll month. A vendor promising "live in two weeks" without saying which one is measuring - always ask which.
The AI modules sit apart from that payroll calendar. The HR assistant, employee surveys and performance reviews work as soon as your environment is set up, even if the payroll connector isn't fully configured yet. Only sending performance data through to your payroll provider waits on that connector.
What comes out of your old system, and in what form?
That depends on where you're coming from. In Belgium the main route runs through your payroll provider (social secretariat).
Route 1: via your payroll provider (the standard in Belgium)
Your payroll data sits with your payroll provider, and that's the most reliable source you have: it's the data your salaries are already calculated on today. If your provider is connected, Peepel retrieves it via the connection. What comes across depends on your provider. Typically:
- Your employee files - the personal and address data your payroll runs on
- The contracts - salary, working schedule, work regime, contract type, joint committee
- The fixed benefits - meal vouchers, eco vouchers, company car, phone and internet allowance, group insurance
- Your org structure - departments, cost centres, work locations
- Leave balances - what each employee has today
- Past payslips (with Attentia, Besox, Daenens, Securex and SD Worx)
In short: with a connected payroll provider, what your payroll runs on today comes across, and you don't have to retype anything from an old system. If your provider doesn't work with Peepel yet (Partena, Group S, UCM), Peepel imports your data from an export.
Route 2: from your existing HRIS
If you're coming from Officient, Peepel pulls your data directly through the connection. If you're coming from Personio or another HRIS, Peepel imports your data from an export of that system, in consultation with you.
One agreement matters here: after a set date, no one works in the old system anymore. Anything booked in your old tool after that doesn't carry over. So you agree on one cutoff date, and Peepel pulls the final state after that.
What you still need to supply yourself
One category doesn't come across automatically anywhere: leave that's already approved for a date in the future. That sits in your old system as a request, and it needs to be in Peepel before the first payroll run goes out - otherwise those days will be missing from performance data. Peepel pulls those over via an export where possible, and sets them up manually otherwise.
Key takeaway: in Belgium your payroll provider is the source of truth for payroll data. Your old HR tool supplies what isn't there: future leave days, and soft data such as teams and assets.
What happens to the connector with your payroll provider?
Your payroll provider stays your payroll provider. Peepel doesn't replace the payroll engine: salary calculation, wage withholding tax and DmfA stay with your provider. Peepel becomes the layer where the HR work happens, and delivers the payroll input (worked time, absences, contract and pay changes). For Dimona, it depends on your provider. With Attentia, Besox and Daenens, Peepel submits the Dimona IN and OUT itself and follows up on the NSSO response. With Securex, Securex files it based on the hire recorded in Peepel. With other providers, Dimona runs through your provider.
The connector itself is set up by your account manager at the payroll provider, together with Peepel. They make sure every type of leave, every pay element and every expense comes through exactly the way your payroll provider expects it.
That sounds like a detail, and it's the step where a migration stalls if it isn't finished. Leave that isn't correctly mapped disappears silently: the day sits approved in the system and never reaches your payroll provider. That's exactly why Peepel and your account manager take care of this work for you.
Key takeaway: Peepel feeds the payroll engine, it doesn't replace it. Responsibility for salary calculation, wage withholding tax and DmfA stays with your payroll provider.
More on that split of roles: automating payroll processing and automating Dimona filing.
Who does what?
The starting point: Peepel carries out the migration. You don't get a homework list of export formats and column names.
| Step | Peepel | You | Payroll provider |
|---|---|---|---|
| Setting up the connector with the provider | Builds and tests | - | Grants access and confirms the codes |
| Retrieving and loading data | Executes | Points to the source | Supplies the payroll data |
| Getting leave types to come through correctly | Executes | Confirms which leave types you use | Confirms the codes |
| Data check before go-live | Delivers the overview | Signs off | - |
| Future leave days | Prepares | Confirms the list | - |
| Inviting employees | Prepares | Sends and communicates | - |
| First performance push | Executes and checks | Approves | Processes |
On your side, the HR manager is enough. You don't need an IT project, a steering committee or an external consultant. The only step that genuinely sits with you is signing off on the data check, and that's deliberate: you're the only one who knows whether those 22 leave days are correct.
That's also what the Sapient number above comes back to. If more than a quarter of implementations miss expectations and nearly a quarter miss adoption, the logical conclusion isn't "more project management." It's: put less work on the client, and keep the one step that genuinely requires domain knowledge - is this data correct? - with the client.
Why the switch falls on the 1st of a payroll month
Peepel goes live with a hard cutoff on the 1st of a payroll month. From that point on, there's one system where bookings happen.
That's a process agreement. Two systems running at once means two places where a leave request can come in, two leave counters drifting apart, and at the end of the month a reconciliation where nobody knows anymore which version is correct. The confusion you want to avoid is exactly the confusion a parallel period creates.
In practice:
- Your payroll month runs out in your old setup, complete and closed
- The 1st of the following month is the first day bookings happen in Peepel
- The first performance push goes out at the end of that month
Key takeaway: one agreed cutoff date, one system, one leave counter. The clarity is the reason.
Want to see what this means for your setup? Book a 30-minute demo - we'll walk through your current system and payroll calendar concretely.
What typically goes wrong in an HR migration?
Almost never the import itself. Imports succeed. What goes wrong, you notice a month later - and by then the migration problem looks like an ordinary HR problem.
These are the four moments you'll feel it.
1. The first payslip is wrong
Someone gets paid three leave days too few, or their meal vouchers aren't on it. That's the classic, and it's also the most expensive: your employee notices it before you do, and your trust in the new system is gone instantly.
That's why there's one moment in the process that never gets skipped: the data check before go-live. You get an overview of every file, contract and leave balance as it sits in Peepel, and you sign off. Because you're the only one who knows whether those 22 days are correct.
2. Approved leave has disappeared
Your employee booked vacation for October back in June. Your old system knows that, the new one doesn't - and so the October payroll run doesn't know it either.
This is the only category that doesn't come across automatically anywhere. Peepel pulls those days across where possible and sets them up manually otherwise, but you confirm the list.
3. The wrong type of leave
Leave isn't a single concept in Belgium. Birth leave paid by the employer is different from birth leave through the health insurance fund. Parental leave falls partly to the employer and partly to a benefit scheme. Every payroll provider expects it delivered in its own way.
Classic HR software shows you that full list and lets you choose yourself. That's exactly where the error creeps in: your HR manager isn't a payroll specialist, and shouldn't have to be.
Peepel solves this on the back end. Your employee simply requests parental leave from X to Y. Peepel splits it correctly itself and delivers it the way your payroll provider expects it. The choice list your team sees is deliberately shorter than the reality behind it.
That's the difference between software that organises your work and software that executes it. A system of workflow gives you the choice list. A system of execution knows the rule and applies it.
4. Nobody uses it
The quietest failure, and the most common one. The system is there, the data is correct, and three months later half your team is still emailing their leave requests.
That's the gap Sapient exposes: 91% of organisations say they do change management, 7% set aside budget for it. One announcement on go-live day isn't an adoption plan. Plan for a short walkthrough per team and one clear point of contact in the first month - that's the cheapest insurance in the whole process.
Key takeaway: a migration rarely fails technically. It fails on a wrong payslip, missing leave, or a team that simply doesn't use the new system. Don't ask your vendor whether the import will work - ask who catches these three.
What do you do with your old system?
Two questions that always come up, and the answer is the same for both: no rush.
Your old HR tool. Don't cancel it before your first payroll run through Peepel has gone correctly. One month of overlap in your subscription is far cheaper than the one situation where you'd still need it. You stop working in it - you just keep it around briefly as reference.
Your archive. For documents, Belgium has a retention obligation that reaches further back than what an HR system needs to display. Our rule is simple: keep your existing archive as an archive. That's the safest route with any system switch, even if you weren't moving to Peepel.
Beyond that, there's little that can't come along. The more specific your current setup, the more attention we give it - custom fields, custom categories and non-standard structures come along too. What's worth transferring in your case comes up in the demo.
What level is your HR at?
A migration is a good moment to decide where you want to go. Four questions, and your first "yes" is your level:
- Does your HR live in Excel, email and folders? Then you're at Level 1: Manual.
- Do you have one place where all employee data sits, but you still do every task yourself? That's Level 2: System of Record - the classic HRIS.
- Do requests and approvals flow through automatically, but you still click through everything? That's Level 3: System of Workflow.
- Do you give an instruction and the work is done? That's Level 4: System of Execution - agentic HR.
The jump most companies make during a migration is from 2 to 3. The jump that actually removes the work is the one to 4. And that's the reason not to treat a migration as moving the same boxes into a new house: if you migrate from level 2 to level 2, you've invested a migration in the same work.
More on this: what is agentic HR and agentic HR vs. traditional HRIS.
Considering a switch?
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Further reading: Digitising HR processes · HR automation guide · Best HRIS Belgium 2026 · Peepel vs. Personio
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