How to Send an Invoice: Email, PDF & Getting It Paid
Email, PDF attachment, accounting portal, or even a messaging app — how you deliver an invoice affects how fast it's paid. Here's what works for each channel and the mistakes to avoid.
Email + PDF: still the standard
Email with a PDF attachment remains the standard: it's universal, archivable, and prints cleanly. Generate a clean PDF (no watermarks — they look unprofessional to clients), attach it, and write a short message:
'Hi [Name] — attached is invoice INV-042 for [project], totaling $X, due [date]. Payment details are on the invoice. Thanks!'
Three lines. The invoice does the talking; the email just delivers it.
When clients have their own systems
Some clients — especially larger companies — will ask you to upload invoices to their AP portal (Coupa, SAP Ariba, etc.) or email a specific billing address. Do it their way without arguing; fighting a client's payment system only delays your money.
Always keep your own copy with the invoice number in the filename (INV-042-acme-corp.pdf). When the client asks 'can you resend invoice 42?' in eight months, you'll find it in seconds.
Timing and follow-up
Send the invoice the day the work is done. Then: nothing until the due date passes. On day 1 overdue, one polite nudge. Most 'late' payments are just disorganized inboxes, not malice — a single reminder resolves the majority.
Never send invoices via channels that disappear (Stories, disappearing messages). You need a paper trail — for follow-ups, for taxes, and for the occasional dispute.
Related definitions
Put it into practice — free
Billia's invoice generator applies everything on this page automatically: numbering, totals, tax, and a clean PDF.
Create my invoice — freeFrequently asked questions
Is email or paper better for sending invoices?
Email with a PDF attached is the standard: it's instant, free, and creates a paper trail. Paper still works for clients who ask for it, but it's slower and easier to lose.
What should the email say when I send an invoice?
Keep it short: what the invoice covers, the amount, the due date, and a note that the PDF is attached. A polite one-liner like 'Please let me know if you have any questions' is all the cover letter you need.
How do I know the client received my invoice?
Ask for a quick confirmation on first invoices with a new client. Billia emails the PDF to the address you enter, so you know exactly where it went — then a short follow-up message a few days later confirms it landed.
What if the client never opens the invoice email?
Follow up: a friendly nudge at 7 days, a firmer one at 14, and a phone call after that. Most 'unopened' invoices are just buried inboxes, not refusals — a reminder is usually all it takes.