Show HN: Hacienda-CLI – CLI to reconcile Spanish tax returns with the tax agency (github.com)

A new command-line interface (CLI) tool named Hacienda-CLI has been introduced to simplify the process of reconciling Spanish tax returns with the Agencia Tributaria (AEAT) by allowing users to download their fiscal data and upload XML declarations seamlessly. Designed to work in tandem with AI agents like Claude or ChatGPT, this tool aids users in generating valid XML files for tax submissions while emphasizing that users must manually present and sign their declarations. Key commands include user authentication, data downloading, XML uploading, and validation, ensuring compliance with the official AEAT schemas for the 2025 tax season. The significance of Hacienda-CLI lies in its ability to bridge the gap between fiscal data management and AI assistance, making the tax filing process more efficient. With the absence of a REST or SOAP API for the Modelo 100, the CLI leverages Playwright for direct browser interactions, enabling actions like downloading HTML data and validation against the official XML Schema Definition (XSD). Its user-friendly integration supports iterative corrections, as users receive real-time feedback on errors during XML submissions, thus enhancing the accuracy of tax filings in Spain. The tool's extensible nature also suggests potential for future adaptations to handle other tax models, broadening its applicability in the tax preparation landscape.