Client (Mandant)
A Mandant (client) is a self-contained, accounting-wise and organizationally independent unit within an ERP installation – usually a legally separate company with its own data set.
A Mandant (client) is a self-contained, accounting-wise and organizationally independent unit within an ERP or accounting software. Technically, a client bundles all data – master data, documents, postings, accounts and reports – that belong to exactly one distinct business entity. In practice, a client almost always corresponds to a legally independent company: a limited company (GmbH), a stock corporation (AG), a sole proprietorship or a subsidiary with its own obligation to prepare financial statements.
The term originally comes from the data-center and DATEV world, where a tax advisor kept the books of many "clients" (Mandanten) separately. In modern ERP systems it denotes the top-level separation layer: two clients share the same software installation but, by default, see nothing of each other. Each client has its own number range, its own chart of accounts and its own data sovereignty – as if it ran on a separate system.
At a glance
- Top-level data separation layer in the ERP – usually a legally independent company
- Own chart of accounts, own document numbers and separate reports per client
- Several clients run on one shared software installation
- Data separation is strict: by default one client sees none of the other’s data
- Foundation for group structures, franchises and tax-advisor mandates
How is a client structured?
A client combines two kinds of data: client-specific data that belongs to it alone and – depending on the system – shared configuration data used by all clients. Client-specific data includes accounts receivable and payable, item and customer master records, all documents from quotation to invoice, as well as every journal entry and balance. Shared, on the other hand, may be technical settings, user accounts, roles or tax-key templates.
Every client has a unique key – often a client number – that is internally attached to each record. This key ensures that a report, a document or a posting is always assigned to exactly one client and never accidentally "spills over" into another.
Master data, documents and accounting per client
Within a client, the complete business structure repeats itself: its own chart of accounts (e.g. SKR 03 or SKR 04), its own number ranges for invoices and orders, its own cost centers and a standalone annual financial statement. Two companies in the same ERP can thus maintain different charts of accounts, currencies or fiscal years without interfering with each other. Likewise, each client stores its own company master data – name, address, tax number and VAT identification number – which automatically appear on the documents and in the tax filings of exactly that client.
Why a client matters
The central benefit of a client is the clean legal and economic separation of several companies while sharing the same IT. A company with a holding and several subsidiaries can map all units in a single ERP, each as its own client – saving the operation, maintenance and licensing of multiple separate systems.
At the same time, each company’s accounting stays audit-proof and separate: every client produces its own balance sheet, its own advance VAT return and its own reports. For tax advisors and auditors this separation is mandatory – every legal entity must be presentable as accounting-wise independent. Despite the separation, consolidated group reports can be generated across client boundaries if the system supports it.
The client in the ERP system
Almost every ERP asks, at login or in the system settings, which client is being worked in. The software then automatically filters all views, lists and reports to that client. A software’s ability to run several such units cleanly separated in one installation is called multi-client capability (Mandantenfähigkeit) – a key selection criterion for corporate groups and for cloud ERP providers that serve many customers on shared infrastructure.
Technically, the separation is implemented in different ways: either through separate databases per client, through separate schemas, or through a shared database with a client identifier in every table. For the user the difference is invisible – what matters is that permissions and data visibility reliably end at the client.
Permissions and client assignment
The rights management controls which users may see and edit which clients at all. A clerk may, for example, only access the sales client, while group accounting works on several clients in parallel. This assignment is an essential building block of data protection and internal control: it prevents one company’s documents or revenues from becoming visible to unauthorized people in another.
DACH specifics
In German-speaking countries the client concept is closely tied to the DATEV system: for decades tax advisors have kept their clients as separate Mandanten with their own client number. When exporting data to DATEV or BMD, a separate posting batch is handed over per client, uniquely identifying the chart of accounts (SKR 03/04) and the advisor/client number.
The separation also applies to GoBD-compliant retention: every client must keep its documents and postings in an unalterable and traceable form. In a tax audit, a single client – i.e. one legal entity – is always examined. A clean client structure is therefore not only a technical but also a legal necessity.
In Austria and Switzerland the same basic logic applies, only with different frameworks: in Austria the chart of accounts follows the standard chart of accounts (Einheitskontenrahmen), in Switzerland usually the SME chart of accounts (Kontenrahmen KMU), and for the tax-advisor export BMD often takes on DATEV’s role in Austria. Companies operating internationally also often set up a separate client per country to cleanly separate differing currencies, tax rates and reporting obligations.
Example
Example: trading group with three companies in one ERP
A mid-sized trading group runs a sales GmbH, a logistics GmbH and a holding. Instead of operating three separate systems, it sets up all three as separate clients in one ERP installation. Each client has its own chart of accounts, its own invoice number ranges and its own advance VAT return.
The accounting team works with one login that may see all three clients, switching via client selection. Sales support, by contrast, is only authorized for the sales GmbH and never sees the logistics data. At year-end each client produces its own balance sheet; for the bank, an additional consolidated group report is pulled across all three clients.
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