Contents
Migrating data from old software takes six steps: inventory, extraction, cleanup, field mapping, test import, cutover. In my estimator, a simple migration is priced at $900 (€800)excl. VAT; it costs more when the data is old, duplicated or locked in a proprietary format.
Changing software is scary for one specific reason: the fear of losing ten years of customers, history and pricing. That fear is legitimate, but data migration is very manageable with a method. Here is the one I use, what it costs, and the decisions that are yours to make.
The six steps of a successful migration
| Step | What happens | Who is involved |
|---|---|---|
| 1. Inventory | List of the data to migrate, where it lives and how much there is | You and me |
| 2. Extraction | Export from the old software: CSV, Excel, API or direct database access | Me, with your credentials |
| 3. Cleanup | Duplicates, empty fields, inconsistent formats, obsolete records | Me, with your decisions |
| 4. Mapping | Every old field finds its place in the new tool | Me, approved by you |
| 5. Test import | Full load into a test environment, with numeric checks | Your teams verify |
| 6. Cutover | Final export, final import, old tool switched to read-only | Together, on a date you choose |
The test import is the step you never skip. It reveals surprises (a “phone” field that holds addresses, reused customer codes) while there is still time to fix them.
Where the data comes from, and how to extract it
The extraction method depends on the old software.
- Recent off-the-shelf software: most offer CSV exports or an API. This is the simplest case.
- Older software installed on a server: the database is often directly accessible, even when the vendor offers no full export.
- Access, FileMaker or in-house apps: the tables are readable, but the logic (calculations, statuses) has to be understood before it is rebuilt. See modernizing an Access or FileMaker application.
- Shared Excel files: often the slowest to clean up, because every user has their own data entry habits. See turning Excel into an app.
Before canceling a SaaS subscription, check the contract and the tool itself to see what you can export, and in what format. Attachments and history are often harder to retrieve than the records themselves.
What is better left behind
A migration is a chance to clean house. Bringing over useless data makes the tool heavier and can create a compliance issue.
- Prospects who never converted, years ago. The French data protection authority’s guidance on commercial data processing (CNIL, in French) states that prospect data can be kept for three years from collection or last contact, and customer data for the length of the business relationship plus three years after it ends (checked in October 2026). Rules differ by country if you operate outside France.
- Duplicates and test records.
- Fields nobody fills in anymore.
Accounting records have their own legal retention period (the CNIL guidance cites the example of a 10-year accounting obligation in France). They can stay in a separate, searchable archive without cluttering the new tool. This page does not replace advice from your accountant or a lawyer on retention periods.
The decisions that are yours
The technical side is my job, but some decisions can only be made by you. I prepare them as closed questions so they do not hold up the project:
- Which record to keep when two records describe the same customer with different information?
- Which cutover date: month end, quarter end, a quiet period?
- Which checks validate the migration: number of active customers, total outstanding balances, revenue for the year?
- Who keeps access to the old tool after cutover, and for how long?
These calls take one or two short meetings with the person who knows the data best day to day, often sales administration or accounting.
How much a data migration costs
In the estimator, the “data migration” module is priced at $900 (€800)excl. VAT. That covers a simple migration: one or two clean sources, a few thousand records, an obvious field mapping.
The cost goes up with:
- the number of sources to merge (old software + Excel files + shared mailboxes);
- the state of the data: ten years of duplicates take several days to clean up;
- history: migrating past orders and invoices, with their links, takes longer than migrating records;
- attachments: documents, photos and PDFs to attach to the right records.
For a heavy migration, I start with an audit of the sources (express audit at $660 (€589)excl. VAT) to give a fixed price. The migration is then included in the business app quote and tested before go-live, like everything else.
When a migration is not needed
Sometimes the right decision is to bring over almost nothing:
- if the old tool only holds outdated or unreliable data, starting from a clean base is faster;
- if the volume is small, having the team enter it during onboarding can cost less than a migration script;
- if the old software stays in place for another function, connecting the two tools can avoid a migration altogether.
I will tell you during scoping if the migration costs more than it is worth.
Where to start
- List your sources: software, files, shared inboxes, with rough volumes.
- Get a sample export from each source, even a partial one.
- During the discovery call, we look at those exports together to assess the state of the data.
- During scoping, the migration is priced and scheduled, with the cutover date and the checks your teams will run.
Cutover ideally happens during a quiet period for your business, with the old tool kept read-only while you verify.
Frequently asked questions
Can we recover data from software whose vendor no longer exists?
Often, yes. If the software still runs, its database can usually be read directly, or its exports and printouts can be used. The work takes longer and is priced after reviewing the files available.
Do we need to bring over the full history?
Not necessarily. Bring over what is used day to day (active customers, products, open orders) and archive the rest as read-only. Accounting records must remain accessible for their legal retention period, but not necessarily in the new tool.
How long should the old software stay available?
I recommend keeping it read-only for a few weeks to a few months after cutover, while you check that nothing is missing. After that, a complete archived export is usually enough.
Who checks that the imported data is correct?
Your teams, using checks we prepare together: record counts, totals, sample records. Nobody knows your customers, prices and data quirks better than they do.