camt053-loader-mt940: MT940 → camt.053 loader

Convert legacy SWIFT MT940 bank statements into the same camt053 data model as native camt.053 input. A single parse_mt940(text) call returns a camt053.models.ParsedDocument, ready for every downstream consumer in the suite (writer, validator, reversal builder, MCP and LSP servers).

Latest release: v0.0.14. SWIFT MT940 is scheduled for retirement in November 2028. This loader bridges the 2-year window where banks still produce MT940 but downstream tooling expects camt.053.

Contents

• Overview
• Install
• Quick Start
• Supported Fields
• Examples
• The camt053 suite
• When not to use camt053-loader-mt940
• Development
• Security
• Documentation
• License
• Contributing
• Acknowledgements

Overview

camt053-loader-mt940 is a small, focused companion to the camt053 ISO 20022 cash-management library. It does one thing well: parse the common-denominator MT940 grammar shipped by EU and UK commercial banks, and hand back the same ParsedDocument shape that the camt.053 XML parser produces. The rest of the suite then works unchanged.

This package is part of the camt053 suite, a set of independently installable packages that share the camt053.services layer:

• camt053 - the core library (CLI + REST API)
• camt053-mcp - the Model Context Protocol server for AI agents
• camt053-lsp - the Language Server Protocol server for editors
• camt053-writer-xlsx - Excel .xlsx writer for parsed statements
• camt053-loader-mt940 - this package, the MT940 loader

Install

camt053-loader-mt940 runs on macOS, Linux, and Windows and requires Python 3.10+ and pip. It pulls in camt053 automatically and has no other runtime dependencies.

pip install camt053-loader-mt940

Quick Start

from camt053_loader_mt940 import parse_mt940

mt940 = """:20:STMT-REF-1
:25:COBADEFFXXX/DE89370400440532013000
:28C:42/1
:60F:C260620EUR1000,00
:61:2606210621CR500,00NMSCREF1//CREF1
:86:Customer payment for invoice 123
:62F:C260621EUR1500,00
"""

document = parse_mt940(mt940)

print(document.msg_id)
# STMT-REF-1
print(document.statements[0].account.iban)
# DE89370400440532013000
print(document.statements[0].balances[0].amount)
# 1000.00

That's a camt053.models.ParsedDocument, ready to feed to camt053-writer-xlsx (Excel output), the camt053 REST API, or any other consumer in the suite.

Supported Fields

Reversal detection

A :61: line whose debit/credit indicator is RD (reversal of debit) or RC (reversal of credit) becomes an Entry with reversal_indicator=True. Direct support for SEPA / NACHA / CBPR+ return-reason mapping is on the v0.0.2 roadmap.

Unknown fields

Unrecognised tags (e.g. :13D: creation timestamp, bank-specific extensions) are silently ignored, so future SWIFT additions do not break parsing. This follows Postel's law: be liberal in what you accept.

Examples

Two runnable examples live in examples/:

• 01_minimal_parse.py - the smallest valid MT940 + parse + inspect.
• 02_round_trip_to_xlsx.py - MT940 in, Excel .xlsx out (requires camt053-writer-xlsx).

Both are exercised in CI on every commit.

The camt053 suite

camt053-loader-mt940 is part of a set of independently installable packages built around the camt053 library — pick whichever ones your stack needs:

flowchart LR
    A["MT940 text"] -->|parse_mt940| B["camt053-loader-mt940"]
    B -->|ParsedDocument| C["camt053"]
    C -->|writer / validator / reversal / MCP / LSP| D["Downstream consumers"]

When not to use camt053-loader-mt940

• You already have native camt.053 input. Use the camt053 core parser directly — this loader is the bridge for legacy MT940-only data sources, not an alternative for native camt.05x.
• You need MT941 / MT942 (intraday-balance / intermediate-statement messages). Out of scope today; the data model supports adding them if you'd like to contribute a separate loader.
• You need bank-specific :86: sub-field parsing (e.g. Deutsche Bank's ?20 / ?30 / ?32 GVC codes). The raw :86: value is preserved verbatim in TransactionDetails.additional_info; downstream tooling can parse it if needed.
• You need direct ISO return-reason mapping for RD / RC lines. Currently reversal_indicator=True is set; mapping to ISO ExternalReturnReasonCode is on the v0.0.2 roadmap.
• Your MT940 is PGP / GPG encrypted. Decrypt upstream and pass the plaintext to the loader.

Development

git clone https://github.com/sebastienrousseau/camt053-loader-mt940
cd camt053-loader-mt940
python -m venv .venv && source .venv/bin/activate
pip install -e ".[dev]"
pytest                          # 100% line + branch coverage gate
interrogate camt053_loader_mt940  # 100% docstring gate
mypy camt053_loader_mt940       # strict

Security

camt053-loader-mt940 parses a flat text format with no XML envelope — the XXE / billion-laughs surface lives upstream in the camt053 core (defusedxml + xml_guard). Field regexes are anchored and bounded, so catastrophic backtracking is not a concern. Reporting practice, supported versions, and supply-chain posture (PyPI Trusted Publishing, sigstore attestations, signed tags) are documented in SECURITY.md. Vulnerabilities go via GitHub Private Vulnerability Reporting, not public issues.

Documentation

• README.md — this file
• CHANGELOG.md — release notes
• SECURITY.md — disclosure + supported versions
• SUPPORT.md — how to get help
• MAINTAINERS.md — who can merge
• examples/ — runnable scripts, exercised in CI

License

Licensed under the Apache License, Version 2.0. Any contribution submitted for inclusion shall be licensed as above, without additional terms.

Contributing

Contributions are welcome. Open an issue or PR on the repository.

Acknowledgements

Built on the camt053 ISO 20022 Bank Statement library. The MT940 grammar follows the SWIFT User Handbook MT940 specification and the common-denominator subset shipped by major EU and UK commercial banks.