Grundsteuer Digital

Overview

GrundsteuerDigital is a SaaS platform for Germany’s property tax reform. Property owners and their advisers use it to prepare property data and submit it digitally to the tax authorities. DATEV recommends the platform. Contrive Solutions built it as a multi-tenant, white-label product that 7 partners run under their own brand, including Volksbank, Sparkasse and smartsteuer.

What the client needed

Germany’s property tax reform meant property owners had to file new property tax declarations. The client wanted one platform that could handle these submissions end to end and that partner organisations could offer to their own customers under their own name. Each partner needed its own look, a secure login, and a way to charge for submissions. Every submission had to be checked before it went to the tax office.

What we built

Multi-tenant white-label SaaS: one code base serving 7 partners, each with custom theming on its own subdomain.
Tax authority and accounting integrations: connections to ELSTER (German tax filing), Lexoffice and OS-FINO.
OAuth / SSO login: partners’ users sign in with their existing accounts.
Credit-based payments: users buy credits and spend them on submissions.
Submission validation: property data is checked before it is submitted, so errors are caught early.

Tech stack

Back end: Laravel on PHP 7.4
Front end: Vue 3 with Vuex
Real-time updates: Pusher
Database: MySQL with horizontal sharding, so data is split across database servers as partners and users grow
Hosting: AWS