HR System Migration (2026): How It Actually Works | Peepel
Gert-Jan Vermote · 8 min · 2026-09-03
A migration to Peepel is one to two weeks of work and goes live on the 1st of a payroll month. Here's what moves, who does what, and what typically goes wrong.
Key takeaways
- Moving the data over is one to two weeks of work; go-live falls on the 1st of a payroll month.
- In Belgium your payroll provider (social secretariat) is the source of truth: files, contracts, fixed benefits and leave balances all come from there.
- Peepel carries out the migration; on your side, the HR manager signing off on the data check is enough.
- Hard cutoff on the 1st of the payroll month: no parallel period, one leave counter that's correct.
- Migrations rarely fail on the import - they fail on a wrong payslip, missing leave, or adoption that never happens.
Anyone searching for "HR system migration" has usually already made the decision. The question isn't whether you're switching anymore, it's 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 one to two weeks of work. That's the time between handing over the data and a Peepel environment where your employee files, contracts and leave balances are correct. The cleaner your starting point, the closer you sit to one week; the more exceptions and mismatched counters, the closer to two.
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: the work itself is one to two weeks; the wait for the first payroll run is set by the payroll calendar. 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), not your old HR tool.
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. Peepel retrieves it via the connector. What comes across:
- 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
In short: everything your payroll runs on today comes across. You don't have to retype anything from an old system.
Route 2: from your existing HRIS
If you're coming from Officient, Personio or another HRIS, Peepel handles the import 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 and doesn't take over the statutory filings - salary calculation, wage withholding tax, DmfA and Dimona stay there. Peepel becomes the layer where the HR work happens, and delivers performance data monthly.
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 this work sits with Peepel and your account manager, not with you.
Key takeaway: Peepel feeds the payroll engine, it doesn't replace it. Responsibility for salary calculation and statutory filings 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, not a technical limit. 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, not the speed.
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 it looks like an ordinary HR problem, not a migration 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. Not because it's your job, but 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. Not because we expect something to go wrong, but because 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 we look at it instead of dropping 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 spent two weeks of work reproducing the same work.
More on this: what is agentic HR and agentic HR vs. traditional HRIS.
Considering a switch?
A 30-minute demo is the fastest way to see whether your current setup is migratable and what it involves in your specific situation.
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Further reading: Digitising HR processes · HR automation guide · Best HRIS Belgium 2026 · Peepel vs. Officient · Peepel vs. Personio
Peepel is an agentic HR platform headquartered in Ghent. ISO 27001 certified, GDPR compliant, data hosted in the EU. More on our trust page and about us.
FAQ
- How long does a migration to a new HR system take?
- Moving the data over is one to two weeks of work. Go-live falls on the 1st of a payroll month, so the calendar decides when your first payroll run through the new system happens.
- Do we have to re-enter everything during an HR migration?
- No. Your employee files, contracts, fixed benefits and leave balances carry over from your payroll provider or your existing HRIS. Only leave already approved for a future date needs separate attention.
- Who carries out the migration?
- Peepel carries out the migration. On the client side, the HR manager is enough - they sign off on the data check and handle communication to employees.
- Do we run a period twice during the switch?
- No. Peepel goes live with a hard cutoff on the 1st of a payroll month, so there's always one system where bookings happen and one leave counter that's correct.
- What happens to past payslips and documents?
- Your recent payslips carry over, so employees can find them in Peepel. Everything published in Peepel after go-live stays available there. You keep your existing archive as an archive, which is the safest route with any system switch.
- Can we already use Peepel before the payroll connector is finished?
- Yes. The AI modules work independently of the payroll connector. Only sending performance data through to the payroll provider waits on that configuration.
- Does the payroll provider keep the same role after a migration?
- Yes. Salary calculation, wage withholding tax, DmfA and Dimona stay with the payroll provider. Peepel delivers the performance data and handles the HR work that precedes it.
- Why do HR implementations run over so often?
- Not because of the import, but because of what's not right afterwards. In the HR Systems Survey by Sapient Insights Group (2024, 3,318 organisations), more than a quarter of organisations missed their implementation expectations and 23% missed their adoption expectations, while only 7% set aside the recommended change-management budget.
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