How-To Guide• 6 min read • Updated April 2026

How to Send an Invoice Online — 4 Methods (Fastest First)

1Send via Invoice Generator (Fastest — Recommended)

  1. 1Create your invoice in the tool
  2. 2Click "Send via Email"
  3. 3Enter your client's email address and a brief message
  4. 4Click Send — the PDF is attached automatically
  5. 5You are notified when the client views the invoice and when they pay

2Email Invoice as PDF Attachment

  1. 1Download your invoice as PDF
  2. 2Compose a new email
  3. 3Use a clear subject line: "Invoice INV-2026-001 from [Your Name] — Due [Date]"
  4. 4Attach the PDF
  5. 5Write a brief professional message in the email body
  6. 6Send

3Share an Invoice Link

  1. 1Some invoice tools generate a unique URL for each invoice
  2. 2Share the link by email, WhatsApp, or any messaging platform
  3. 3Client views the invoice in their browser — no PDF download required
  4. 4Client can pay directly from the link if you have a payment gateway connected

4Through a Payment Platform (PayPal, Stripe)

  1. 1Log in to PayPal or Stripe
  2. 2Use the built-in invoicing feature to create an invoice
  3. 3Send via the platform — client receives a payment link
  4. 4Client pays online directly — funds appear in your account
  5. 5Downside: transaction fees apply (typically 2.9% + fixed fee)

Best Email Subject Lines for Invoices

"Invoice INV-2026-001 from [Your Name] — Due 5 May 2026"
"[Your Business] Invoice for [Project Name] — $2,500 due 5 May"
"Payment Request: Invoice #001 — [Client Name] — Due [Date]"

Email Body Template

Subject: Invoice INV-2026-001 from [Your Name] — Due 5 May 2026 Hi [Client Name], Please find attached Invoice INV-2026-001 for [project/service description], totalling [Amount]. Payment is due by 5 May 2026. You can pay by [bank transfer/PayPal/Stripe — insert your details]. If you have any questions, please don't hesitate to reach out. Thank you for your business. [Your Name] [Your Phone] [Your Website]

What to Do After Sending an Invoice

Day 3

If no payment or acknowledgement, send a friendly check-in: 'Just wanted to confirm you received invoice INV-001. Please let me know if you have any questions.'

Day 8

Send a polite reminder noting the invoice is overdue: 'I'm following up on invoice INV-001, which was due on [date]. Please advise on the expected payment date.'

Day 15

Firm notice: 'Invoice INV-001 remains unpaid. As per our terms, a late fee of 2% per month now applies. Please arrange payment by [new date].'

Day 30+

Issue a formal letter of demand. Consult a debt collection service or small claims court for amounts that justify it.

Frequently Asked Questions

Is it OK to send an invoice by email?▼

Yes. Email is the standard method for sending invoices online in most industries. Send as a PDF attachment with a clear subject line referencing the invoice number and amount.

Should I send the invoice before or after completing the work?▼

Send it immediately when work is delivered — not before (unless requesting a deposit) and not at the end of the month. Immediate invoicing starts the payment clock and keeps the work fresh in the client's mind.

How many times should I follow up on an unpaid invoice?▼

Day 3 (friendly check-in), Day 8 (polite reminder with late fee notice), Day 15 (firm overdue notice), Day 30+ (formal demand letter). Most invoices are paid after the first or second reminder.

Send Invoices Online Free — No Sign-Up

Create, download PDF, and email invoices directly from the tool in one step.

Create & Send Invoice Free

Related Resources

Invoice Payment Terms GuideHow to Generate an InvoiceInvoice vs ReceiptFreelancer Invoice Generator