Before the button works
On a new invoice, Invoice readiness lists what is still missing. Save & send stays off until the blockers are clear. The usual ones:
A confirmed tax profile, a company registration number, or a withholding suggestion can also block the first send. Those checks depend on the country on your company. They are in Rules for your country. Full versus simplified invoices are in Invoice settings.
Send it
On the new-invoice wizard the steps are Details, Line items, Payment, and Review & send. Save draft keeps the invoice and does not email anyone. It still has a temporary reference. Save & send saves and emails the customer. Use this while it is still a draft you are willing to send. Issue & send on an invoice that is ready to become the legal document registers it, locks the number series, then sends it. After that, the invoice is the document you correct with a credit note, not by editing the issued lines. The customer opens it in Client Hub. Preview PDF and Email preview show what they will see before you send. Message to customer is the note in that email. Wording defaults live under Invoice settings → Email & SMS.How they can pay
On Payment, turn on the methods this invoice should offer:
If no method is on, the section says No payment method enabled.
