Omani VAT-registered businesses face a phased Oman Tax Authority (OTA) e-invoicing mandate that requires structured, machine-readable invoices rather than the free-form PDFs ERPNext prints by default. Out of the box, ERPNext gives you Sales Invoice and POS Invoice DocTypes, item-level tax templates, and a print-format engine, but it has no concept of an Oman-compliant e-invoice XML, no submission lifecycle, no OTA-specific field validation (buyer/seller VAT identifiers, mandated invoice categories, rounding and tax-summary rules), and no way to track acceptance or rejection responses. Finance teams end up bridging that gap with spreadsheets and manual portal entry, which does not scale past a few branches and breaks the moment the mandate tightens.

ECOSIRE builds a proper Frappe app for your ERPNext instance that closes this gap. The app ships as an installable module with its own DocTypes — for example an Oman E-Invoice document that links back to the source Sales/POS Invoice, plus a submission-log DocType for the audit trail. We wire generation into ERPNext's document lifecycle through hooks.py doc events (on_submit, on_cancel) and server scripts, so submitting an invoice deterministically produces the OTA-aligned XML payload, applies the 5% VAT tax template, validates the mandatory fields before anything is transmitted, and records the response. Whitelisted Python methods exposed over the Frappe REST API let you (or an external POS/middleware) trigger generation and query status programmatically, while client scripts surface a clean status indicator and action buttons directly on the invoice form.

Technically, the app is built to keep upgrades sane: business rules live in server scripts and Python controllers rather than customized core files, configuration lives in a single settings DocType (endpoints, credentials, company VAT registration, environment toggles), and permissions are enforced through dedicated roles and a role profile so only authorized finance users can regenerate or resubmit. A scheduler event handles retries and status reconciliation for anything queued or provisionally accepted, and multi-branch/multi-company setups map each company's VAT registration and numbering to the correct payload. Reporting is delivered as Frappe query/script reports plus a dashboard so you can see submitted, accepted, rejected, and pending counts at a glance. The app targets Frappe/ERPNext v15 and v16.

Because this is build-to-order, nothing ships until we agree on scope. Delivery is typically one working week from confirmed scope, depending on which OTA phase applies to you, your POS/integration surface, and the number of legal entities. We start with a short scoping call, install and configure on a staging copy of your ERPNext, run UAT against your real invoices, then cut over to production with a rollback plan and a post-go-live support window. You receive the source code for your version and the git repository, so you are never locked out of your own compliance tooling.