German accounting teams running Odoo hit the same wall when they reconcile with DATEV: every customer needs a debitor account number that fits the SKR03/SKR04 numbering ranges (commonly the 10000–69999 debitor band), and Odoo core has no concept of it. Out of the box you either leave partner.ref blank, type numbers by hand into a spreadsheet, or bolt on a fragile pre-export step. The results are duplicate numbers, gaps that break the DATEV/ASCII export, and a Steuerberater who sends the file back. It gets worse at scale — a sales team creating dozens of customers a week cannot be trusted to remember the next free number in a shared sequence.

We build a focused Odoo module that generates the DATEV debitor number automatically and deterministically. Technically, it extends res.partner with a stored, indexed debitor field and hooks the assignment into the ORM: a create/write override (or an ir.actions.server automated action) fires when a partner first becomes a customer, draws the next value from a dedicated ir.sequence bounded to your configured DATEV range, and guards against collisions with a SQL unique constraint plus a pre-write check so two concurrent sales users can never claim the same number. A @api.depends-driven compute keeps any display/mirror fields in sync, and the assigned number flows into partner.ref (or a custom field) so the standard DATEV export and your account.move postings pick it up with no extra manual step.

Configuration lives in a small settings model: start number, range ceiling, zero-padding width, and whether numbers are reused when a partner is archived. Where you run multi-company or several accounting books, we scope the sequence per company so each entity keeps its own contiguous debitor range. Everything ships with ir.model.access.csv rules plus record rules so only accounting roles can edit the number, an XML/OWL settings view for the configuration, and — when useful — a QWeb report or list export of the debitor register for your tax advisor. We can also expose read access over Odoo's XML-RPC/JSON-RPC API so an external DATEV-side tool can pull the mapping. The module targets Odoo 17.0, 18.0, and 19.0 and works on both Community and Enterprise (Enterprise's DATEV-specific accounting features are respected, not duplicated).

Delivery is build-to-order: it starts with a short scoping call to confirm your chart of accounts (SKR03 vs SKR04), the exact debitor range, multi-company layout, and how existing customers should be back-filled. We then build against your Odoo version on a staging copy, run UAT with you, and deploy with a rollback plan; typical delivery is 2–4 weeks from confirmed scope. Pricing starts from $249 (indicative, single-company base scope); multi-company debitor ranges, migration of large existing customer bases, and deeper DATEV/export integration increase the quoted scope.