Branch IDWew in KSeF: company and internal-unit details

IDWew identifies an internal unit; it does not replace the company's NIP. Under the Ministry's permission model dedicated to a branch or internal unit, its IDWew must appear on each invoice in Podmiot3/DaneIdentyfikacyjne. This is a condition of that model, not a requirement for every sole trader to create a branch.

Purchase invoice

Where the taxpayer is the buyer and the purchase concerns its internal unit, buyer details including NIP belong in Podmiot2. Unit details, particularly IDWew, go in Podmiot3. These are two identifiers with different functions.

Sales invoice

Where the taxpayer is the seller and the sale concerns the unit, the seller's NIP is in Podmiot1. Unit details and IDWew again belong in Podmiot3. The handbook links this representation to issuing and accessing invoices within the described unit permissions. Entering the identifier alone does not grant someone permissions.

What to check when access is missing

As an organisational check, confirm you use this permission model, the invoice contains the correct unit IDWew, and the taxpayer's NIP is on the correct transaction side. This checks data; it is not instructions for creating an identifier or granting permissions. Source: Ministry handbook, §2.2.5.

FAQ

Does IDWew replace NIP?

No. NIP identifies the taxpayer; IDWew identifies its unit for the described KSeF model.

Where is the unit entered on a purchase invoice?

In Podmiot3 with its IDWew; the taxpayer buyer and its NIP remain in Podmiot2.

Does every business need IDWew?

This condition concerns the dedicated internal-unit permission model. It does not require every business to create a unit or IDWew.

Source and limits

KSeF 2.0 handbook, part II, August edition, §2.2.5, checked on 7 October 2026; its cover states the legal position as at 1 February 2026. This concerns Poland and excludes local-government and VAT-group models, creating IDWew and legal classification of a branch.