camt053: ISO 20022 Bank Statements and Reversing Entries

Read ISO 20022 camt Bank-to-Customer Cash Management messages, extract booked entries by return reason code (e.g. AC04 Closed Account), and generate validated reversing entries — the core of a modern, AI-assisted treasury stack with native MCP and LSP integrations.

Latest release: v0.0.5 — namespace-agnostic camt.052/053/054 parsing and one-shot reversing-entry generation, validated against the official ISO 20022 camt.053.001.14 schema, for Python 3.10+. See what's new →

Contents

• Overview
• Install
• Quick Start
• Features
• Usage
• Supported messages
• Architecture
• Examples
• The camt053 suite
• When not to use camt053
• Development
• Security
• Documentation
• License
• Contributing
• Acknowledgements

Overview

camt053 reads ISO 20022 camt cash-management messages — the standardised bank-to-customer statements (camt.053), account reports (camt.052), and debit/credit notifications (camt.054) — into a typed model, lets you filter booked entries by ISO external return reason code, and generates a validated reversing entry for the matching transactions.

The headline capability is the one-shot reversing-entry workflow: read an incoming camt.053 statement, find the entries carrying a return reason code (e.g. AC04 Closed Account), and emit a validated reversing entry — answering the prompt-engineering dream:

"Read this incoming bank statement XML, parse out the transactions with error code AC04, and automatically generate the reversing entry."

• Documentation: https://sebastienrousseau.github.io/camt053/
• Source code: https://github.com/sebastienrousseau/camt053
• Bug reports: https://github.com/sebastienrousseau/camt053/issues

A single shared facade (camt053.services) backs four developer surfaces — the Python API, the CLI, the REST API, and the companion MCP and LSP servers — so every interface behaves identically. This package is part of the camt053 suite (all Python 3.10+):

flowchart LR
    A["Inbound camt.05x XML"] -->|parse| B["camt053.services"]
    B -->|filter by reason code| C["AC04 entries"]
    C -->|reverse + validate| D["camt.053.001.14 reversing entry"]

Install

camt053 runs on macOS, Linux, and Windows and requires Python 3.10+ and pip.

python -m pip install camt053

python -m venv venv
source venv/bin/activate        # macOS/Linux
venv\Scripts\activate           # Windows
python -m pip install -U camt053

Quick Start

from camt053 import services

# An incoming camt.053 statement (truncated for brevity — see examples/).
statement_xml = open("statement.xml", encoding="utf-8").read()

# Find the entries returned AC04 (Closed Account).
ac04 = services.filter_entries(statement_xml, "AC04")
print(f"{len(ac04)} AC04 entr{'y' if len(ac04) == 1 else 'ies'}")

# Generate the reversing entry: parse -> filter -> reverse, in one call.
reversal_xml = services.generate_reversal(statement_xml, reason_code="AC04")
print(reversal_xml)  # validated camt.053.001.14 document

Or from the command line:

# Generate a reversing entry for every AC04 entry on a statement
camt053 reverse -i statement.xml -r AC04 -o reversal.xml

# List the entries on a statement (filter by reason, status, date, or amount)
camt053 entries -i statement.xml -r AC04
camt053 entries -i statement.xml --status BOOK --from 2026-06-01 --min 1000

# Export the (filtered) entries as CSV or JSON, to stdout or a file
camt053 entries -i statement.xml --export csv -o entries.csv
camt053 entries -i statement.xml -r AC04 --export json

# Choose the output format: a Rich table (default) or structured JSON
camt053 entries -i statement.xml --format json
camt053 reverse -i statement.xml -r AC04 --format json   # JSON envelope

# Inspect the parsed statement as JSON, or validate an identifier
camt053 parse -i statement.xml
camt053 validate-id -k iban -v GB29NWBK60161331926819

# Validate an incoming statement against its official ISO camt XSD
camt053 validate -i statement.xml

parse, entries, reverse, and validate accept -i - to read from stdin, so they compose in a pipeline.

New to camt.053? The 10-minute quickstart walks the full install, validate, parse, reverse workflow with real commands and output.

Features

• Parse camt.053 / camt.052 / camt.054 into a typed, JSON-serialisable model. Parsing is namespace-agnostic, so every ISO version (.001.01 through .001.14) and real-world bank file is read.
• Filter booked entries by ISO external return reason code (AC04, AC06, MD07, …), and by status, booking-date range, and amount range (all ANDed) via services.filter_entries(...) or the camt053 entries flags.
• Return reason codes — a substantial slice of the ISO 20022 ExternalReturnReason1Code set (the common SEPA / CBPR+ return reasons), listed via camt053 reasons, with case-insensitive lookup through services.validate_reason_code(code) -> {"code", "name", "valid"}.
• Reason-code action policy — classify a return reason into a handling action ("return", "retry", or "ignore") via services.classify_reason(code) -> {"code", "name", "action"}, with a sensible built-in default (account-level rejections return, transient conditions such as AM04 / AM05 retry, informational reasons ignore). The full mapping is services.reason_policy(); both accept an overrides mapping and a custom default. The camt053 reasons table shows the action column and camt053 classify -r AC04 classifies a single code.
• Export the (filtered) entries to CSV or JSON (camt053 entries --export {csv,json} [-o file]); CSV columns are reference, amount, currency, credit_debit_indicator, status, booking_date, value_date, reason_code.
• Structured output — camt053 entries --format json emits the entries as a JSON array, and camt053 reverse --format json emits a {"message_type", "reason_code", "xml"} envelope instead of raw XML (--format table, the default, keeps the Rich table / raw XML).
• Reverse — generate a camt.053.001.14 reversing entry from the matching entries (credit/debit indicator flipped, RvslInd set, return reason carried in RtrInf), in one call.
• Validated output — generated reversals are checked against the official ISO 20022 camt.053.001.14 XSD bundled with the package.
• SWIFT charset cleansing — opt-in cleansing of the name / narrative fields (Nm / AddtlInf / party / counterparty names) bound for SWIFT FIN / CBPR+ rails: characters outside the SWIFT X set are transliterated (é → e, ß → ss, smart quotes / dashes folded) or stripped, and field maximum lengths are enforced. Enable it on the reversal path with services.generate_reversal(xml, cleanse=True) / services.generate(records, cleanse=True) (default off, so existing output is unchanged), or cleanse records directly with services.cleanse_records(records) -> {"changed", "fields": [report, ...]}, which returns an audit report of exactly what changed. Cleansed reversals still validate against the bundled XSD.
• Validate incoming statements — services.validate_statement(xml) (and the camt053 validate command) check an inbound camt.052 / camt.053 / camt.054 document against the matching official ISO 20022 XSD, detected from its namespace, returning {"valid", "message_type", "errors"}.
• Re-serialise (round-trip) — render a parsed ParsedDocument / Statement back to a validated camt.053.001.14 document via services.serialize_statement(xml) (or camt053.serialize_document(doc) / camt053.serialize_statement(stmt)). The output is deterministic and round-trip stable: parse_document(serialize_statement(parse_document(xml))) preserves the account, balances, and entries (references, amounts, currencies, credit/debit indicators, and return reasons).
• Safe by default — XML is parsed with defusedxml (XXE / billion-laughs safe); output paths are traversal-checked.
• One facade, four interfaces — the CLI, REST API, MCP server, and LSP server all call camt053.services.
• IBAN / BIC / LEI validators (ISO 13616 / 9362 / 17442).
• Decimal amounts & ISO 4217 currencies — Entry.amount_decimal / Balance.amount_decimal parse the string amount into a Decimal (the string is kept verbatim for XML fidelity), and services.validate_currency(code) -> {"code", "valid", "minor_units"} checks a code against a bundled ISO 4217 set and reports its minor units (EUR=2, JPY=0, …).
• Typed (mypy --strict) and tested (100% coverage), validated against the official ISO 20022 business samples.

Usage

from camt053 import parse_statement, services

# A minimal incoming camt.053 statement: a EUR 1,500 credit transfer that was
# booked, then returned because the beneficiary account was closed (AC04).
statement_xml = """<?xml version="1.0" encoding="UTF-8"?>
<Document xmlns="urn:iso:std:iso:20022:tech:xsd:camt.053.001.14">
  <BkToCstmrStmt>
    <GrpHdr><MsgId>STMT-MSG-0001</MsgId><CreDtTm>2026-06-15T08:00:00</CreDtTm></GrpHdr>
    <Stmt>
      <Id>STMT-0001</Id><CreDtTm>2026-06-15T08:00:00</CreDtTm>
      <Acct><Id><IBAN>GB29NWBK60161331926819</IBAN></Id><Ccy>EUR</Ccy></Acct>
      <Bal><Tp><CdOrPrtry><Cd>CLBD</Cd></CdOrPrtry></Tp>
        <Amt Ccy="EUR">10000.00</Amt><CdtDbtInd>CRDT</CdtDbtInd>
        <Dt><Dt>2026-06-15</Dt></Dt></Bal>
      <Ntry>
        <NtryRef>NTRY-0001</NtryRef>
        <Amt Ccy="EUR">1500.00</Amt><CdtDbtInd>CRDT</CdtDbtInd>
        <Sts><Cd>BOOK</Cd></Sts>
        <NtryDtls><TxDtls>
          <RtrInf><Rsn><Cd>AC04</Cd></Rsn></RtrInf>
        </TxDtls></NtryDtls>
      </Ntry>
    </Stmt>
  </BkToCstmrStmt>
</Document>"""

# 1. Parse into the typed model.
statement = parse_statement(statement_xml)
print(statement.account.identifier())          # -> GB29NWBK60161331926819
print(len(statement.entries))                   # -> 1

# 2. Select the entries returned AC04 (Closed Account).
ac04 = statement.entries_with_reason("AC04")
print(ac04[0].amount, ac04[0].credit_debit_indicator)   # -> 1500.00 CRDT

# 3. Generate the validated reversing entry (the original CRDT becomes DBIT).
reversal_xml = services.generate_reversal(statement_xml, reason_code="AC04")
assert "<RvslInd>true</RvslInd>" in reversal_xml
assert "<CdtDbtInd>DBIT</CdtDbtInd>" in reversal_xml

Supported messages

The parser is namespace-agnostic and reads every ISO version of these messages; the official XSDs for .001.01–.001.14 are bundled under camt053/xsd/. Reversing entries are emitted as camt.053.001.14.

Architecture

flowchart TD
    CLI["Click CLI"] --> S["camt053.services"]
    API["FastAPI REST API"] --> S
    MCP["camt053-mcp"] --> S
    LSP["camt053-lsp"] --> S
    S --> P["parse/ — statement_parser, reason_codes"]
    S --> R["reversal/ — reversal builder"]
    S --> X["xml/ — template + official ISO XSD"]
    S --> V["validation/ — IBAN, BIC, LEI, JSON Schema"]

Error handling

Every exception in camt053.exceptions inherits from Camt053Error and carries a stable, machine-readable code. These codes are part of the public API — they are guaranteed unique and will not change across releases — so you can switch on exc.code (e.g. to map a failure onto an HTTP status) without depending on the class name or message text.

from camt053 import services
from camt053.exceptions import Camt053Error

try:
    services.generate_reversal(statement_xml, reason_code="AC04")
except Camt053Error as exc:
    log.error("[%s] %s", exc.code, exc)

Robustness

The statement parser is built for the messy reality of inbound bank files: malformed-but-recoverable statements degrade gracefully rather than failing outright.

• Missing optional elements (owner name, currency, balances, booking date, return reason, ...) read as None / empty — only the <Document> envelope wrapping a recognised camt.05x container is mandatory.
• Unknown or extra elements (vendor extensions, unexpected siblings) are ignored: children are matched by local name, not by a fixed schema.
• Unexpected namespaces and prefixes are tolerated — a prefixed <camt:Document> root, a missing namespace, or a non-ISO namespace URI all parse the same way.

Genuinely non-well-formed XML (unclosed / mismatched tags, bad entities) still raises StatementParseError, which carries the 1-based source line (and column, where reported) so the offending byte can be located. See camt053/parse/statement_parser.py for the documented recovery limits.

Examples

Runnable, self-contained scripts live in examples/:

git clone https://github.com/sebastienrousseau/camt053.git && cd camt053
python examples/reverse_ac04.py

The camt053 suite

camt053 is the core of a set of independently installable packages — pick whichever ones your stack needs:

The MCP, LSP, writer-xlsx, and loader-mt940 packages are thin wrappers over the shared camt053.services facade exported here, so every interface behaves identically.

When not to use camt053

• You need to generate payment files (pain.001 Customer Credit Transfer, pain.008 Direct Debit). Use pain001 — the sibling library for outbound ISO 20022.
• You need to parse pacs.* (FI-to-FI) messages. Out of scope; this library targets the camt.05x (Bank-to-Customer) family only.
• You need bank API transport (PSD2, EBICS, SWIFTNet). camt053 reads files and emits files; it does not move them. Pair with a dedicated transport library.
• You need a GUI. This is a library + CLI + REST API; the closest thing to a UI is the LSP server's in-editor diagnostics.
• You need real-time processing (FedNow / TIPS / RTP). Those rails use camt.052 intraday reporting, not camt.053 end-of-day statements; the parser accepts camt.052 but the reversing-entry workflow is camt.053-shaped.

Development

camt053 uses Poetry and mise.

git clone https://github.com/sebastienrousseau/camt053.git && cd camt053
mise install
poetry install
poetry shell

A Makefile orchestrates the quality gates (kept in lockstep with CI):

make check        # all gates (REQUIRED before commit)
make test         # pytest with coverage (100% gate)
make lint         # ruff + black --check
make type-check   # mypy --strict
make examples     # run the example scripts

Security

camt053 is the entry point for untrusted XML from banks for every consumer in the suite. Defence-in-depth is taken seriously: parsing uses defusedxml (XXE / billion-laughs neutralised), a pre-flight xml_guard enforces a configurable byte cap and refuses inline DOCTYPE / ENTITY declarations, and the REST API additionally caps request bodies via middleware. Reporting practice, supported versions, fix-window SLAs, and the full supply-chain posture (PyPI Trusted Publishing, sigstore attestations, signed tags) live in SECURITY.md. Vulnerabilities go via GitHub Private Vulnerability Reporting, not public issues.

News / Releases

• 2026-06-22 — Shipping camt053 v0.0.6 for the 14-16 November 2026 ISO 20022 cliff (v0.0.6 release announcement + Nov 2026 cliff narrative).

Documentation

• README.md — this file
• CHANGELOG.md — release notes
• ROADMAP.md — milestones and the explicit Declined/Deferred list
• GOVERNANCE.md — decision model + becoming a maintainer
• SECURITY.md — disclosure + supported versions + supply chain + NIST SSDF mapping
• SUPPORT.md — how to get help, by need
• MAINTAINERS.md — who can merge and cut releases
• CONTRIBUTING.md — submission process + style
• STYLEGUIDE.md — cross-suite style guide (linked from every package README)
• docs/quickstart.md — 10-minute install, validate, parse, reverse tutorial
• docs/deployment-cookbook.md — Docker Compose / systemd / Kubernetes recipes for the REST API
• docs/version-matrix.md — supported camt.05x revisions with the Nov 2026 cliff
• examples/ — runnable scripts, exercised in CI
• docs/ — extended reference (API, quickstart, deployment cookbook)
• Hosted Sphinx docs: https://sebastienrousseau.github.io/camt053/

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 — see the contributing instructions. Thanks to all contributors.

Acknowledgements

Built on Click, Rich, Jinja2, xmlschema, defusedxml, and FastAPI, against the official ISO 20022 camt.05x schemas.