Create and Send an Invoice

An invoice is the official document you send to a client to request payment for a service or product you have delivered. In Prometheus, creating and sending an invoice takes less than 5 minutes.

By the end of this guide: your client will have received an invoice by email with an automatically assigned invoice number, the total amount due, and your payment details.

Before You Begin

You will need:

  • Your client’s details (name, address, email address) — if they are not yet in your contact list, add them first in the Reach module
  • A clear description of the service or product you are billing for
  • The amount and the applicable VAT rate (if you are VAT-registered)

Step 1 — Open the Invoices List

  1. In the left menu, click Business Suite
  2. In the submenu that appears, click Invoices
  3. The list of all your invoices appears (it will be empty if this is your first invoice)

Step 2 — Create a New Invoice

  1. Click the New Invoice button in the top-right corner
  2. A blank invoice form opens

What you see: a structured document with several sections — client information, date, line items, and totals.

Step 3 — Select Your Client

  1. Click in the Customer field
  2. Start typing your client’s name — a dropdown list will show matches from your contact list
  3. Click on your client’s name to select them

If your client does not appear, they are not yet in your contacts. Close this form, go to the Horizon module, add your client, then come back to create the invoice.

Step 4 — Set the Date and Due Date

  1. The Invoice Date field is pre-filled with today’s date — change it if needed
  2. The Due Date tells your client when payment is expected. The default is 30 days after the invoice date. Adjust it according to your payment terms.

Step 5 — Add Invoice Lines

This is where you describe what you are charging for.

  1. Click Add a Line
  2. In the Description field, type the name of your service or product (e.g. “Website redesign — Phase 1”)
  3. In Quantity, type the number of units (e.g. 1)
  4. In Unit Price, type the price before tax for this line (e.g. 1500)
  5. Select the applicable VAT rate from the dropdown (0%, 5.5%, 10%, or 20% depending on your situation)
  6. Prometheus automatically calculates the total amount including VAT for this line

Repeat steps 1–6 for each service or product you want to include.

Step 6 — Review the Totals

At the bottom of the form, Prometheus automatically displays:

  • Net Total (sum of all lines before VAT)
  • VAT (the calculated tax amount)
  • Grand Total (what your client owes you, including VAT)

Check that all figures match what you expected.

Step 7 — Save and Send

  1. Click Save to store the invoice without sending it — useful if you want to review it first
  2. Check every detail one final time
  3. Click Send by Email
  4. A confirmation window shows your client’s email address — verify it is correct
  5. Click Confirm

What your client receives: an email with your invoice attached as a PDF, including the invoice number, the total due, and your payment details.

What Happens Next

The invoice now appears in your list with the status Sent. When your client pays, mark the invoice as paid by opening it and clicking Mark as Paid. Your financial dashboard updates automatically.

Frequently Asked Questions

Can I edit an invoice after sending it? No — a sent invoice is an official document. If you made a mistake, you need to issue a credit note (a correction invoice). Prometheus generates one automatically when you open the invoice and click Create Credit Note.

My client did not receive the email. What should I do? Wait 5 minutes — emails can sometimes be slightly delayed. Then check that your client’s email address is correct in the Reach module. You can also resend the email from the invoice by clicking Resend.

Is the invoice number assigned automatically? Yes. Prometheus generates a sequential invoice number automatically, compliant with local legal requirements (e.g. 2026-001, 2026-002…).