A client of ours recently told us she lost a $5,000 payment because the invoice went to her client's spam folder and nobody followed up for two weeks. The fix was simple: a clear subject line, a PDF attachment, and a 48-hour follow-up.
Email is the most common delivery method, but it's also the easiest for clients to overlook. We recommend sending the invoice, then following up within 48 hours to confirm receipt. A simple 'just checking the invoice came through' is often enough. For larger invoices or new clients, use a service that provides delivery confirmation. For consistently late payers, switch to a payment-on-receipt model — but agree to this upfront. Whatever method you choose, consistency matters: send every invoice the same way, at the same time relative to the work completed, and follow up on the same schedule.
How you deliver an invoice significantly impacts how quickly you get paid. Following professional email etiquette, attaching clean PDF documents, and offering clear payment links reduces friction.
This guide covers standard email subject line formats, postal mail and client portal delivery options, and a practical 3-step follow-up timeline for overdue payments.
Content reviewed for accuracy against current tax authority guidelines (IRS, HMRC, EU Council).
⚡ Key Takeaway
Send invoices as PDF with a clear subject line (e.g., 'Invoice #INV-001 — Due 2026-02-15'), payment terms, and a direct payment link.
Keep the email polite, clear, and concise. State the invoice number, total amount due, payment due date, brief summary of work, attached PDF file name, and direct payment link or bank details.
Send the invoice immediately upon project completion or on agreed recurring billing dates (e.g. 1st or 15th of the month). Immediate invoicing reduces payout turnaround time.
Send a courteous email 3 days before the due date, on the due date, and 7 days after the due date with a copy of the attached invoice. Reiterate payment terms and offer to answer any questions.