BSN on Employee

The Burgerservicenummer (BSN) is the Dutch citizen service number —
every resident has one. As an employer, you're legally required to record
it for every Dutch employee and to handle it with the same care as a
health record under the AVG (Dutch GDPR).

This module adds an encrypted BSN (Burgerservicenummer) field to the
Employee doctype, but only if HRMS is installed — there's no point
adding it on a bench that doesn't have payroll/HR.

Where it lives

After installation, open any Employee record. Below the Passport
Number field you'll see BSN (Burgerservicenummer) — a masked
password-style input. Type the 9-digit number; it accepts spaces and
strips them. Save.

The value is encrypted at rest using Frappe's field-level encryption (the
same mechanism that protects API keys and database passwords). Anyone
opening the Employee record sees masked dots — even System Managers. Only
code that explicitly decrypts the value can read it back.

Elfproef validation

Dutch BSNs aren't just 9 digits — they follow the elfproef (11-test):
a weighted digit sum that must be divisible by 11. The module validates
this on every save:

• The first 8 digits are weighted 9, 8, 7, 6, 5, 4, 3, 2.
• The 9th digit is weighted –1.
• The total must be divisible by 11.

Typos and made-up numbers fail this check immediately. If save fails,
recheck the BSN against the employee's ID document — there's almost
certainly a digit transposed.

The validator strips spaces and dashes before checking, so 123 456 789
and 123-456-789 and 123456789 all work the same way.

Compliance notes

Under Dutch and EU law, BSN is a bijzondere persoonsgegeven (special
category personal data). Storing it means you must:

• Limit who can read it. Use ERPNext's role-permission system to
  restrict Employee read access to HR roles only.
• Have a legal basis. Employment is one; you can't store BSNs for
  contractors or job applicants without separate justification.
• Have a retention policy. BSN should be deleted when the employment
  relationship ends and the legal retention period (seven years for
  payroll records) lapses.
• Document the processing. Your AVG processing register should
  include "BSN voor loonadministratie" as a stored data category.

This module enforces the encryption-at-rest and elfproef-validation
pieces; the role permissions and retention policy are your call to set
up.

What you can do with it

Most operators never need to read the BSN back in plain text — payroll
tools that need it can call ERPNext's encryption API. For ad-hoc reads
(e.g. confirming a value with the employee), open the record, click into
the field, and the value reveals while you have it focused.

If you're integrating a third-party payroll system, that integration
will need to decrypt the field; your developer can use Frappe's standard
password-field read API. Don't put the BSN into custom reports or
exports unless the export channel is encrypted end-to-end.