Your guide to compliant invoicing

1 Introduction

This guide is for anyone who creates, submits, or reviews invoices in Zoho Books at an organization using the Avetium E-Invoicing extension. It covers the day-to-day work of getting an invoice validated by NRS, reading what comes back, and fixing anything that gets rejected.

1.1 What This Extension Does For You

Nigerian businesses are required to submit invoices to NRS (National Revenue Service) for FIRS compliance validation. The Avetium E-Invoicing extension lets you do this without leaving Zoho Books — no separate portal, no re-typing invoice data. You create the invoice as normal, click one action, and the extension handles validation with NRS in the background.

Once validated, the proof of compliance — an official reference number and a scannable QR code — is written straight back onto the invoice you already created.

1.2 How an Invoice Moves Through the System

1.3 Key Terms

2 Before You Submit an Invoice

2.1 What You'll Need

• An authorised Zoho Books user account with access to the Invoices module.
• An invoice that's complete and accurate — customer details, line items, and tax information all feed directly into what NRS sees.
• Nothing else. You don't need a separate Avetium login, API key, or credential of any kind — authentication is handled entirely by your organization's Administrator during setup.

2.2 Checking the Extension Is Ready

Open any invoice in Zoho Books and look at the action menu. If the extension is installed and configured, you'll see a Verify with NRS option alongside the usual actions (Edit, Mails, Share, PDF/Print).

3 Understanding Invoice Status

Every invoice touched by the extension moves through up to four statuses. Knowing what each one means tells you exactly what to do next.

4 Submitting an Invoice to NRS

4.1 Step-by-Step

1. Create or open the invoice in the Zoho Books Invoices module, and complete all required fields as you normally would.
2. Save the invoice and review it — once submitted, corrections to a validated invoice can't be made retroactively.
3. Open the invoice's action menu and select Verify with NRS.
4. A confirmation pop-up appears: “Are you sure you want to perform the custom action?” Click Proceed to continue, or Cancel to go back.
5. The invoice status changes to Submitted while NRS processes it.
6. Once NRS responds, the status updates automatically to either Validated or Rejected — no need to refresh or resubmit anything yourself.

4.2 What Happens After You Click Verify with NRS

From this point, everything happens through Avetium in the background: the invoice is checked against NRS's required fields, submitted for validation, and the result is written back onto the same invoice. You don't need to visit any other system or portal at any point in this process.

5 Reading a Validated Invoice

Once NRS validates an invoice, four things appear directly on it in Zoho Books:

• Invoice Reference Number (IRN) — the unique validation ID.
• CSID — the cryptographic stamp proving NRS validated the invoice.
• A QR code, labelled “Scan to verify with NRS.”
• A validation timestamp — exactly when NRS approved the invoice.

5.1 The Invoice Reference Number (IRN)

The IRN is your invoice's official compliance identifier. If a customer, auditor, or tax authority ever needs proof this invoice was validated, the IRN is the reference to quote.

5.2 The Cryptographic Stamp Identifier (CSID)

The CSID is issued alongside the IRN as cryptographic proof that NRS — and not any other party — validated the invoice. You won't need to do anything with it directly; it's part of the invoice's permanent compliance record.

5.3 The QR Code

Anyone can scan the QR code on a validated invoice to confirm it was genuinely validated by NRS. This is useful when sharing a printed or PDF copy of the invoice with a customer who wants to verify it independently.

6 Handling a Rejected Invoice

6.1 Reading the Rejection Reason

If NRS rejects an invoice, its status changes to Rejected and the rejection reason is displayed clearly on the invoice itself — you don't need to look anywhere else to find out what went wrong. Where possible, the guidance points to the specific field that needs correcting.

6.2 Correcting and Resubmitting

1. Open the rejected invoice.
2. Read the rejection reason and locate the field it refers to.
3. Correct that field on the invoice.
4. Click Correct and Resubmit — this appears directly on the rejected invoice.
5. The invoice follows the same validation flow as a first-time submission (Section 4), and its status updates once NRS responds.

6.3 When to Contact Your Administrator

Most rejections come down to something fixable on the invoice itself — a missing tax detail, an incomplete address, a mismatched TIN. But if the rejection reason references something you don't have access to change (for example, an organization-level setting), that's a configuration issue for your Administrator, not something to fix invoice by invoice.

7 Working with Inbound Supplier Invoices

Inbound invoices are invoices your suppliers send you, validated through the same NRS process, that arrive in your Accounts Payable module rather than your Invoices module.

• A supplier submits their invoice to NRS through the Avetium platform.
• Once validated, Avetium matches it to your organization using your TIN.
• The invoice appears in Purchases → Bills, already carrying its IRN, CSID, QR code, supplier details, and tax breakdown.

From there, you process the bill exactly as you would any other bill in Zoho Books — no extra steps are required on your end.

8 Notifications You Might See

9 What You Can and Can't Do

As an authorised Zoho Books user, here's where your access begins and ends:

10 Troubleshooting & Common Questions

11 Getting Help

Start with your organization's Zoho Books Administrator — they manage the extension's connection and configuration, and can resolve most issues directly or escalate to Avetium Support on your behalf.

If you're reporting a problem, it helps to have ready:

• The affected invoice number.
• What you expected to happen versus what actually happened.
• A screenshot of any error or rejection message shown on the invoice.

12 Quick Reference Guide

Use this table as a fast lookup for common day-to-day tasks.