ksef 0.2.8

Python interface for the KSEF API

ksef

NOT PRODUCTION READY

A python library for Polish KSEF (National e-invoice system, original: Krajowy System e-Faktur) system.

The official KSEF API documentation can be found at https://github.com/CIRFMF/ksef-docs/tree/main.

IMPORTANT Currently the project is not even in alpha stage, I barely started working on it. Initially it will support my personal needs only, but I plan to gradually implement new and more complex features.

Using

To add and install this package as a dependency of your project, run uv add ksef (or pip install ksef).

Authentication Setup

The library supports two authentication methods for KSEF API v2:

KSeF Token Authentication

A KSeF token can be generated via the KSeF web portal or obtained through the API after XAdES authentication.

from ksef.auth.token import TokenAuthorization
from ksef.client import Client
from ksef.constants import Environment

auth = TokenAuthorization(
    token="your-ksef-token",
    environment=Environment.TEST,
)
tokens = auth.authorize(nip="1234567890")

client = Client(authorization=auth, environment=Environment.TEST)

XAdES Certificate Authentication

Requires a qualified certificate from a trusted CA, or a KSeF-issued certificate. Provide PEM-encoded certificate and private key bytes.

from pathlib import Path

from ksef.auth.xades import XadesAuthorization
from ksef.client import Client
from ksef.constants import Environment

auth = XadesAuthorization(
    signing_cert=Path("cert.pem").read_bytes(),
    private_key=Path("key.pem").read_bytes(),
    environment=Environment.TEST,
)
tokens = auth.authorize(nip="1234567890")

client = Client(authorization=auth, environment=Environment.TEST)

Environments

• Environment.PRODUCTION — https://api.ksef.mf.gov.pl/api/v2/
• Environment.DEMO — https://api-demo.ksef.mf.gov.pl/api/v2/
• Environment.TEST — https://api-test.ksef.mf.gov.pl/api/v2/

Building Invoices

Basic invoice structure

from datetime import date
from decimal import Decimal

from ksef.models.invoice import (
    Address,
    Invoice,
    InvoiceData,
    InvoiceType,
    Issuer,
    IssuerIdentificationData,
    NipIdentification,
    Subject,
)
from ksef.models.invoice_rows import InvoiceRow, InvoiceRows
from ksef.models.invoice_annotations import InvoiceAnnotations

invoice = Invoice(
    issuer=Issuer(
        identification_data=IssuerIdentificationData(
            nip="1234567890",
            full_name="My Company Sp. z o.o.",
        ),
        address=Address(
            country_code="PL",
            city="Warszawa",
            street="Marszałkowska",
            house_number="10",
            apartment_number="5",
            postal_code="00-001",
        ),
    ),
    recipient=Subject(
        identification_data=NipIdentification(nip="0987654321"),
        address=Address(
            country_code="PL",
            city="Kraków",
            street="Floriańska",
            house_number="1",
            postal_code="30-001",
        ),
        name="Customer Sp. z o.o.",
    ),
    invoice_data=InvoiceData(
        currency_code="PLN",
        issue_date=date(2026, 3, 25),
        issue_number="2026/03/001",
        sell_date=date(2026, 3, 25),
        total_amount=Decimal("123.00"),
        invoice_type=InvoiceType.REGULAR_VAT,
        invoice_annotations=InvoiceAnnotations(),
        invoice_rows=InvoiceRows(rows=[
            InvoiceRow(
                name="Hosting service",
                unit_of_measure="szt.",
                quantity=Decimal("1"),
                unit_net_price=Decimal("100.00"),
                net_value=Decimal("100.00"),
                tax=23,
                delivery_date=date(2026, 3, 25),
            ),
        ]),
    ),
)

Recipient identification types

The library supports all KSeF recipient identification methods:

from ksef.models.invoice import (
    NipIdentification,        # Polish NIP
    EuVatIdentification,      # EU VAT number
    ForeignIdentification,    # Non-EU tax ID
    NoIdentification,         # No tax ID (individuals)
)

# Polish company
id_pl = NipIdentification(nip="1234567890")

# EU company
id_eu = EuVatIdentification(eu_country_code="DE", eu_vat_number="123456789")

# Non-EU company
id_foreign = ForeignIdentification(country_code="US", tax_id="12-3456789")

# Individual (no tax ID)
id_none = NoIdentification()

Tax rates

Invoice rows support all valid KSeF tax rates via the tax field, plus OSS/IOSS rates via tax_oss:

from ksef.models.invoice_rows import (
    InvoiceRow,
    # Standard rates
    TAX_23, TAX_22, TAX_8, TAX_7, TAX_5, TAX_4, TAX_3,
    # Zero rates
    TAX_0_KR,   # 0% domestic
    TAX_0_WDT,  # 0% intra-Community supply
    TAX_0_EX,   # 0% export
    # Special rates
    TAX_ZW,     # exempt from tax
    TAX_OO,     # reverse charge
    TAX_NP_I,   # not subject to taxation
    TAX_NP_II,  # not subject (art. 100)
)

# Standard 23% rate
row = InvoiceRow(name="Service", tax=TAX_23)

# Intra-Community supply at 0%
row = InvoiceRow(name="Goods to EU", tax=TAX_0_WDT)

# OSS rate for EU consumer (e.g. 21% Belgian VAT)
row = InvoiceRow(name="Digital service", tax_oss=Decimal("21"))

Tax summary (P_13/P_14 fields)

For KSeF to display Netto/VAT totals, provide a TaxSummary on InvoiceData:

from ksef.models.invoice import TaxSummary

tax_summary = TaxSummary(
    net_standard=Decimal("100.00"),   # P_13_1 — net at 23%/22%
    vat_standard=Decimal("23.00"),    # P_14_1 — VAT at 23%/22%
)

Available fields:

Fields	Rate	XML
net_standard / vat_standard	23% or 22%	P_13_1 / P_14_1
net_reduced_1 / vat_reduced_1	8% or 7%	P_13_2 / P_14_2
net_reduced_2 / vat_reduced_2	5%	P_13_3 / P_14_3
net_flat_rate / vat_flat_rate	4% or 3%	P_13_4 / P_14_4
net_oss / vat_oss	OSS/IOSS	P_13_5 / P_14_5
net_zero_domestic	0% domestic	P_13_6_1
net_zero_wdt	0% intra-Community	P_13_6_2
net_zero_export	0% export	P_13_6_3
net_exempt	exempt (zw)	P_13_7
net_not_subject	not subject (np I)	P_13_8
net_not_subject_art100	not subject (np II)	P_13_9
net_reverse_charge	reverse charge (oo)	P_13_10

For foreign currency invoices, use the *_pln fields to provide VAT converted to PLN:

TaxSummary(
    net_standard=Decimal("100.00"),        # EUR
    vat_standard=Decimal("23.00"),         # EUR
    vat_standard_pln=Decimal("98.31"),     # P_14_1W — VAT in PLN
)

Foreign currency invoices

For non-PLN invoices, set the exchange rate per row and add descriptions for the rate source:

from ksef.models.invoice import AdditionalDescription

row = InvoiceRow(
    name="Service",
    tax=23,
    unit_net_price=Decimal("100.00"),
    net_value=Decimal("100.00"),
    quantity=Decimal("1"),
    exchange_rate=Decimal("4.2867"),  # KursWaluty per row
)

# NBP rate source as a key-value note
desc = AdditionalDescription(
    key="Kurs waluty",
    value="4.2867 PLN/EUR, tabela kursów średnich NBP nr 056/A/NBP/2026 z dnia 23.03.2026",
)

invoice_data = InvoiceData(
    currency_code="EUR",
    additional_descriptions=[desc],
    # ...
)

Additional recipients (Podmiot3)

For invoices with a third party (e.g. a government receiver/school when the buyer is a city hall):

from ksef.models.invoice import (
    AdditionalRecipient,
    ROLE_RECEIVER,         # 2 — internal unit/branch of the buyer
    ROLE_JST_RECEIVER,     # 8 — government unit receiver
    ROLE_FAKTOR,           # 1 — factoring entity
    ROLE_ADDITIONAL_BUYER, # 4 — additional buyer
)

receiver = AdditionalRecipient(
    identification_data=NipIdentification(nip="9876543210"),
    name="Szkoła Podstawowa nr 1",
    address=Address(
        country_code="PL",
        city="Tarnów",
        street="Słoneczna",
        house_number="15",
        postal_code="33-100",
    ),
    role=ROLE_RECEIVER,
)

invoice = Invoice(
    issuer=issuer,
    recipient=buyer,
    additional_recipients=[receiver],
    invoice_data=invoice_data,
)

Sending an invoice

from ksef.xml_converters import convert_invoice_to_xml

# Convert to XML and send
result = client.send_invoice(invoice)
print(result.reference_number)
print(result.session_reference_number)

# Check status later
status = client.get_invoice_status(
    session_reference_number=result.session_reference_number,
    reference_number=result.reference_number,
)
print(status.status.code)    # 200 = accepted
print(status.ksef_number)    # e.g. "1234567890-20260325-ABCDEF-01"

Integration Tests

Integration tests connect to the live KSEF test environment using real credentials. They are excluded from the default test run and must be invoked explicitly:

source .env
uv run pytest -m integration

Credentials are provided via environment variables. Tests with missing variables are skipped automatically. See tests/integration/README.md for the full list of variables and per-method usage.

Contributing

Prerequisites

1. Set up Git to use SSH

1. Generate an SSH key and add the SSH key to your GitHub account.
2. Configure SSH to automatically load your SSH keys:

   cat << EOF >> ~/.ssh/config
   Host *
     AddKeysToAgent yes
     IgnoreUnknown UseKeychain
     UseKeychain yes
   EOF
   

2. Install Docker

1. Install Docker Desktop.
   • Enable Use Docker Compose V2 in Docker Desktop's preferences window.
   • Linux only:
     • Configure Docker to use the BuildKit build system. On macOS and Windows, BuildKit is enabled by default in Docker Desktop.
     • Export your user's user id and group id so that files created in the Dev Container are owned by your user:

       cat << EOF >> ~/.bashrc
       export UID=$(id --user)
       export GID=$(id --group)
       EOF
       

3. Install VS Code or PyCharm

1. Install VS Code and VS Code's Dev Containers extension. Alternatively, install PyCharm.
2. Optional: install a Nerd Font such as FiraCode Nerd Font and configure VS Code or configure PyCharm to use it.

Development environments

The following development environments are supported:

1. ⭐️ GitHub Codespaces: click on Code and select Create codespace to start a Dev Container with GitHub Codespaces.
2. ⭐️ Dev Container (with container volume): click on Open in Dev Containers to clone this repository in a container volume and create a Dev Container with VS Code.
3. Dev Container: clone this repository, open it with VS Code, and run Ctrl/⌘ + ⇧ + P → Dev Containers: Reopen in Container.
4. PyCharm: clone this repository, open it with PyCharm, and configure Docker Compose as a remote interpreter with the dev service.
5. Terminal: clone this repository, open it with your terminal, and run docker compose up --detach dev to start a Dev Container in the background, and then run docker compose exec dev zsh to open a shell prompt in the Dev Container.

Developing

• This project follows the Conventional Commits standard to automate Semantic Versioning and Keep A Changelog with Commitizen.
• Run poe from within the development environment to print a list of Poe the Poet tasks available to run on this project.
• Run poetry add {package} from within the development environment to install a run time dependency and add it to pyproject.toml and poetry.lock. Add --group test or --group dev to install a CI or development dependency, respectively.
• Run poetry update from within the development environment to upgrade all dependencies to the latest versions allowed by pyproject.toml.
• Run cz bump to bump the package's version, update the CHANGELOG.md, and create a git tag.