Migrating storage customers is the most complex part of the data transfer. The reason: you not only need to enter customer details, but also make sure invoicing continues seamlessly. If this doesn't go well, customers will receive an incorrect invoice.
Note: At this point, we only transfer the storage holders to Bas. We don't import customer details or invoicing data from your old system. You enter everything manually, so you retain control over the data and avoid mistakes.
Important: make sure all customer notifications are turned OFF before you start. With 173 storage case files, you don't want every entry to trigger a message to the customer.
Step 1 - Preparing an Excel list
Most companies keep their storage records in Excel. Prepare a list with the following columns:
Column | What to enter | Example |
Customer name | Full name of the storage customer | The De Vries family |
Contact details | Email and phone | |
Crate/container number | Unique number per container | Container 22 |
Location | Where the container is located | Warehouse 1, Row A |
Rate per container | Monthly amount per container (excl. VAT) | EUR 95.00 |
Last invoiced date | Up to when the customer has already been invoiced | 31-01-2026 |
Step 2 - Cleaning up your data
Check your Excel list before you start importing. Common problems:
Mixed uppercase and lowercase letters - make naming consistent
Phone numbers in the place of email addresses - validate each field
Initials incorrect or missing - fill these in where needed
Duplicate customers - remove duplicates
Tip: Take half an hour to clean up your Excel list. This will save you hours of correction work in Bas later on.
Step 3 - Importing storage case files
Import the storage case files into Bas. You can do this manually (per case file) or via the bulk import feature.
For each storage case file:
Create a new case file
Enter the customer's details (name, address, email, phone)
Select the type "storage"
Add the containers
Enter the rate per container
Set the last invoiced date (see the next step)
Step 4 - Setting the last invoiced date (CRITICAL!)
This is the most crucial part of the entire storage migration. For every storage case file, you set the last invoiced date. This is the date up to which you've already invoiced the customer in your old system.
Why is this so important?
Bas calculates the next invoice based on the last invoiced date. If you enter the storage start date here instead of the last invoiced date, the system will calculate an invoice for the entire storage period. A customer who's been in storage for 2 years would then suddenly receive an invoice for 24 months.
What you enter | What happens |
Last invoiced date (correct) | The system continues invoicing from the correct date |
Storage start date (wrong!) | Customer receives an invoice for the entire storage period |
Example: - The customer has been in storage since 01-03-2024 - You've invoiced up to and including 31-01-2026 - Enter as the last invoiced date: 31-01-2026 - Bas will then continue invoicing from 01-02-2026
Note: This is the most common and the most costly mistake in storage migration. Enter the last invoiced date, NOT the storage start date. Check that this date is correct for every storage case file. Don't rush this.
Step 5 - Setting the rate per container
Enter the rate per container for each storage container. Don't do this at a total level.
Why not at a total level?
Suppose you have a customer with 3 containers. If you put the total amount on 1 container and set the other two to EUR 0, you'll have a problem as soon as one of those containers is emptied out. The container with the amount is removed, and the other two are at zero - then you won't get an invoice at all.
Approach | What you enter | What happens when a container is emptied out |
Per container (correct) | Container 1: EUR 95, Container 2: EUR 95, Container 3: EUR 95 | Container 2 emptied: you still invoice EUR 190 for the other two |
At a total level (wrong!) | Container 1: EUR 285, Container 2: EUR 0, Container 3: EUR 0 | Container 1 emptied: you invoice EUR 0 for the other two |
Step 6 - Converting weekly prices to monthly prices
Many removal companies work with weekly prices for storage, but Bas calculates in months. The formula is:
Weekly price x 52 / 12 = monthly price
Weekly price | Calculation | Monthly price |
EUR 20 per week | EUR 20 x 52 / 12 | EUR 86.67 per month |
EUR 25 per week | EUR 25 x 52 / 12 | EUR 108.33 per month |
EUR 30 per week | EUR 30 x 52 / 12 | EUR 130.00 per month |
Note: The monthly price is slightly higher than what customers are used to with weekly invoicing (a month averages 4.33 weeks, not 4 weeks). Be prepared for questions from storage customers about this.
Step 7 - Adjusting the storage invoice template
Adjust your storage invoice template with a transition note. Add a line such as:
"You're receiving this invoice from our new system. The layout is different from what you're used to, but the content and the amount remain the same."
Include this text in your invoice template so all storage customers automatically receive the explanation with their first invoice.
Note: Remove this transition note from your template again after 2 months. By that time, customers will be used to the new layout and the message is no longer needed.
Step 8 - Informing customers about the system switch
When you switch to Bas, a number of things change for your storage customers:
The invoice looks different (different layout, different system)
The sender's email address may change
The invoicing period and the amount may change
Payment goes via Mollie instead of bank transfer
Send an accompanying message with the first invoice from Bas. This prevents confusion and unnecessary phone calls.
Example text:
Dear [customer name],
We have switched to a new system for our administration. As a result, your invoice looks different from what you're used to. The content and the amount remain the same. If you have any questions, please feel free to contact us.
Kind regards, [company name]
If the invoicing period changes: If the invoicing period changes (for example, from four-weekly to monthly), communicate this explicitly to your customers. Prepare a standard letter you can send out.
Step 9 - Checking the first storage invoicing round
Check per case file:
Is the last invoiced date correct?
Is the rate per container correct (and not zero)?
Is the number of containers correct?
Is the invoicing period correct?
Is the conversion from weekly to monthly rate correct?
If everything is correct, send the invoices. If something isn't correct, adjust the case file and regenerate the invoice.
Tip: Schedule this check for a quiet moment. It takes time, but prevents mistakes that create a lot of work later on. Take the time to thoroughly check every case file during the first invoicing round.
Tips
Start by turning off notifications. With 173 storage case files, you don't want every entry to trigger a message.
Validate your customer data in advance. Check email addresses, phone numbers and addresses in your Excel list. Errors in the source data lead to errors in Bas.
Thoroughly check the first storage invoicing round. Take the time to go through all the draft invoices before sending them.
Prepare a standard letter to send along with the first invoice. This way, customers aren't caught off guard by an invoice from a new system.
Adjust your invoice template with a transition note and remove it again after 2 months.
Please note
Using the start date instead of the last invoiced date for storage customers results in huge overdue invoices. A customer who's been in storage for 2 years would then get an invoice for 24 months. This is the most common mistake in storage migration.
A total price on one container instead of a price per container leads to invoicing problems when a container is emptied out. Always spread the amount across all containers.
Not validating data leads to phone numbers ending up where email addresses should be, missing initials and duplicate customer records. Take the time to clean up your source data.
Not converting weekly prices to monthly prices results in incorrect invoices. Use the formula: weekly price x 52 / 12 = monthly price.
Don't forget to remove the transition note from your invoice template after 2 months.
Next article: Inviting employees to the app