How can I import my existing customers?

Want to quickly and easily add multiple customers to your account? You can seamlessly import a customer list via an Excel file (XLSX or XLS).

Preparation

Do you have customer data spread across different invoices or documents? Then it is important to first consolidate them into one central list.

Tip: Download the sample file in the import dialog to see which columns you can use and what your file should look like.

Example Excel file

Below is an example of what your Excel file could look like:

title	company_type	last_name	first_name	vat_id	vat_country_code	address	address_zip	address_city	address_country	email	telephone
Bakkerij Janssen BV	BV	Janssen	Pieter	0123456789	BE	Kerkstraat 12	9000	Gent	BE	info@bakkerijjanssen.be	+32 9 123 45 67
Marie Dupont		Dupont	Marie			Rue de l’Église 5	1000	Bruxelles	BE	marie@email.be	+32 2 987 65 43
Tech Solutions NV	NV	De Vries	Jan	9876543210	BE	Industrielaan 100	2000	Antwerpen	BE	contact@techsolutions.be	+32 3 456 78 90

Note: The first row must contain the column names (such as title, last_name, etc.). The actual customer data starts from row 2.

How do you import your customers?

In the menu, go to Contacts > Customers.
Click Import in the top right corner.

An “Import customers” dialog opens:

Import settings

Field	Description
File	Drag your Excel file (XLSX or XLS) to the upload area or click to select a file.
Import as	Choose whether to import the contacts as Customer, Supplier, or both.
Contact persons	Choose whether contact persons from your file should also be imported (“Also import”) or not (“Do not import”).
On duplicates	Determine what should happen if a customer already exists: Skip (keep existing), Overwrite (update existing), or Create new (add duplicate). See how are duplicates detected?
Delete customers	Choose whether existing customers should be deleted before import. Options: “No”, “Delete previously imported items”, or “Delete all”.

Click Download sample file at the bottom to download an Excel template with all available columns.

Upload your Excel file.
Check the settings.
Click Import to proceed to the column mapping.

Step 2: Column mapping

After uploading your file, the column mapping screen appears:

On this screen, you map the columns from your Excel file to the correct data fields in NumNum:

Column	Description
Data column	The field in NumNum where the data should go (e.g., Title, Last name, VAT number). Fields marked with * are required.
File column	Select which column from your Excel file should be mapped to this field. Choose “Skip” if you do not want to import a field.
+ Add column	For some fields, you can combine multiple columns (e.g., merge first name + last name into title).

Tip: NumNum automatically recognizes column names that match the sample file. If you used the sample file as a basis, most columns will already be mapped correctly.

Check that all columns are correctly mapped.
Click Continue… to complete the import.

Available data columns

Below you will find an overview of all data columns you can map when importing. The “Column in sample file” shows the column name as it appears in our downloadable sample file - you are not required to use these, but it makes mapping easier.

Basic details

Data column	Column in sample file	Required	Description
Title	`title`	Yes	Name of the company/customer
Last name	`last_name`	Yes	Last name of the customer
First name	`first_name`	No	First name of the customer
Company type	`company_type`	Yes	Legal form of the company (see available values)

VAT details

Data column	Column in sample file	Required	Description
VAT number	`vat_id`	No	VAT number of the company (number only)
VAT country code	`vat_country_code`	No	Country code of the VAT number (see country codes)

Note: Enter the VAT number without country code and without spaces or dots. So “0123456789” and not “BE0123456789” or “0123.456.789”.

Address details

Data column	Column in sample file	Required	Description
Address	`address`	No	Address of the customer
Postal code	`address_zip`	No	Postal code of the customer
City	`address_city`	No	City of the customer
Country	`address_country`	No	Country code of the customer (see country codes)

Contact details

Data column	Column in sample file	Required	Description
Email	`email`	No	Email address of the customer
Phone	`telephone`	No	Phone number of the customer
Mobile	`cellphone`	No	Mobile number of the customer
Fax number	`fax`	No	Fax number of the customer
Website	`website`	No	Website of the customer

Bank details

Data column	Column in sample file	Required	Description
IBAN country code	`iban_country_code`	No	Country code of the IBAN (see country codes)
IBAN	`iban`	No	IBAN of the customer
BIC	`bic`	No	BIC/SWIFT code of the customer

Invoicing settings

Data column	Column in sample file	Required	Description	Options
Document language	`doc_language`	No	Language for documents	`nl`, `fr`, `en`, `de`
VAT percentage	`vat_percentage`	No	Default VAT percentage	`0`, `6`, `12`, `21`
VAT reverse charged	`vat_shifted`	No	VAT reverse charged	`ja`, `nee` (or `yes`, `no`)
Payment term (days)	`payment_term`	No	Payment term in days	Any whole number (e.g., `14`, `30`, `60`)
Automatic reminder	`auto_reminder`	No	Send automatic reminders	`ja`, `nee` (or `yes`, `no`)

Contact persons

Data column	Column in sample file	Required	Description
Contact person first name	`contactperson_first_name`	No	First name of the contact person
Contact person last name	`contactperson_last_name`	No	Last name of the contact person

Peppol details

Data column	Column in sample file	Required	Description
Peppol Scheme ID	`peppol_scheme_id`	No	Peppol Scheme ID (e.g., `0208` for BE KBO)
Peppol Endpoint ID	`peppol_endpoint_id`	No	Peppol Endpoint ID (usually the enterprise number)
Identification Scheme ID	`identification_scheme_id`	No	Identification Scheme ID
Identification ID	`identification_id`	No	Identification ID

Other

Data column	Column in sample file	Required	Description
Internal notes	`private_notes`	No	Private notes (not visible to the customer)
External ID	`external_id`	No	External reference ID (for integrations with other systems)
Sort order	`sort_order`	No	Sort order (number)

Company types

For the “Company type” field (company_type), you can use the following values:

Value	Full name
BV	Besloten Vennootschap
NV	Naamloze Vennootschap
VOF	Vennootschap Onder Firma
CommV	Commanditaire Vennootschap
CV	Coöperatieve Vennootschap
VZW	Vereniging Zonder Winstoogmerk
Stichting	Stichting
Eenmanszaak	Eenmanszaak
BVBA	Besloten Vennootschap met Beperkte Aansprakelijkheid
Maatschap	Maatschap

Country codes

For fields with country codes (vat_country_code, address_country, iban_country_code), use the ISO 3166-1 alpha-2 codes (2 uppercase letters):

Code	Country
BE	Belgium
NL	Netherlands
FR	France
DE	Germany
LU	Luxembourg
GB	United Kingdom
ES	Spain
IT	Italy
AT	Austria
CH	Switzerland

Tip: Always use 2 uppercase letters for country codes. A complete list can be found at ISO 3166-1 alpha-2.

How are duplicates detected?

NumNum checks whether a customer already exists based on the following fields (in order of priority):

VAT number - If the VAT number matches an existing customer, it is considered a duplicate
External ID - If you use an external_id and it matches, this is considered a duplicate
Name + Address - If there is no VAT number, a combination of company name/title and address details is used

Tip: For the most reliable duplicate detection, make sure you enter VAT numbers consistently and correctly.

What happens with duplicates?

Depending on your choice for “On duplicates”:

Option	Behavior
Skip	The existing customer remains unchanged, the row from your Excel is ignored
Overwrite	The existing customer is updated with the data from your Excel
Create new	A new customer is created, even if one with the same details already exists

After the import

After a successful import:

Confirmation - You will see a confirmation screen with the number of imported customers
Overview - You are automatically redirected to the customer overview where you can see your new customers
Verify - It is recommended to randomly check a few imported customers to verify that all data has been transferred correctly

Note: If there were errors during the import (e.g., missing required fields), those rows are skipped. After the import, check whether the number of imported customers matches the number of rows in your Excel file.

Tips for a successful import

File format: Use XLSX or XLS files (Excel)
Country codes always as 2 uppercase letters (BE, NL, FR, DE)
VAT numbers without country code and without spaces or dots
Empty cells are no problem for optional fields
Duplicates: Use “On duplicates” > “Overwrite” to update existing customer data

Need help? Contact our support team - we are happy to assist!