Description

A Société en Participation (SEP) is an occult partnership without legal personality created for project execution. Members (associates) appoint a Gérant (manager) to handle the SEP's financial affairs. The SEP is invisible to external parties. A Mandataire (representative) invoices external buyers in their own name but on behalf of the SEP.

For sales, the Mandataire appears as seller (BG-4) in invoices to external buyers. Sales revenue is attributed to the SEP and recorded by the Gérant. For purchases, the Gérant appears as buyer (BG-7) in supplier invoices. Associates invoice their own contributions to the SEP with the Gérant as buyer. The Gérant may appear as both seller and buyer in their own contribution invoices.

The e-invoicing reform does not change SEP operations, but VAT pre-filling will not match SEP VAT declarations because pre-fill attributes transactions to the Mandataire or Gérant individually, not to the SEP collectively.

Key characteristics

• SEP has no legal personality and is invisible to external parties.

• Mandataire invoices external buyers as seller (BG-4) on behalf of SEP.

• Gérant gets supplier invoices as buyer (BG-7) on behalf of SEP.

• Associates invoice their contributions to SEP (Gérant as buyer).

• Gérant may appear as both seller and buyer in own contribution invoices.

• VAT pre-fill will not match SEP VAT declarations (known discrepancy).

• Gérant can integrate SEP VAT into own declarations or declare separately.

• Mandataire must share sales invoices with Gérant for SEP accounting.

Relationship to other use cases

Use case 37 involves standard e-invoicing flows but with complex party relationships. Use case 14 (Co-contracting) is related, as SEPs are often created within Groupement Momentané d'Entreprises (GME) contexts. Use case 19a (Billing Mandate) applies when the Mandataire acts as Facturant. The VAT pre-fill discrepancy is similar to use case 33 (Margin Regime) in that the pre-fill is acknowledged as incorrect for the actual tax declaration.

Business and tax context

Legal and regulatory framework

SEPs are governed by Articles 1871-1873 of the Code Civil. They have no legal personality and no SIREN. The Gérant manages SEP finances and may declare VAT separately or integrated with their own declarations. The Mandataire invoices third parties in their own name.

Common business scenarios

Construction projects

Multiple contractors form SEP for a large building project.

Consulting consortiums

Multiple firms pool resources for a client engagement.

Joint R&D

Companies collaborate on a research project through SEP structure.

Tax and accounting implications

VAT pre-fill attributes collected VAT to the Mandataire and deductible VAT to the Gérant, rather than to the SEP. This is an acknowledged discrepancy. The Gérant must maintain separate SEP accounting for proper VAT declarations. ERP systems must isolate SEP transactions from the Mandataire's or Gérant's own transactions.

Important: VAT pre-fill will not correspond to actual SEP VAT declarations. Pre-fill attributes to the Mandataire (sales) and Gérant (purchases), not to the SEP. The Gérant must maintain separate SEP records for correct VAT declaration.

Key data requirements

Sales invoices (Mandataire to external buyer)

Field ID	Description	Value
BT-3	Invoice type code	380
BG-4	Seller	Mandataire (in own name, for SEP)
BG-7	Buyer	External buyer

Purchase invoices (supplier to Gérant)

Field ID	Description	Value
BT-3	Invoice type code	380
BG-4	Seller	Supplier (or associate)
BG-7	Buyer	Gérant (on behalf of SEP)

Implementation considerations

Seller considerations

Mandataire

Invoice in own name, track for SEP accounting, and share sales invoices and lifecycle with Gérant

Associates

Invoice contributions to Gérant as buyer.

Buyer considerations

External buyer

Standard invoice processing (unaware of SEP).

Gérant as buyer

Track purchases for SEP accounting separately.

General considerations

• ERP systems must isolate SEP transactions from individual Mandataire or Gérant transactions.

• PA-E should support shared access for the Mandataire to give the Gérant visibility into sales invoices.

Note:

The Gérant needs visibility into all SEP-related invoices (both sales by the Mandataire and purchases) for SEP accounting and VAT declarations. The Sovos solution handles this through its interface with granular role-based permissions, letting the Gérant access and manage SEP invoice portfolios across multiple parties while keeping separation from non-SEP transactions.

SCI mapping

Standard SCI invoice mappings apply. No SEP-specific SCI fields exist. The SEP structure is managed through business logic and party relationships.