Mail an invoice online

Client requirement — Some businesses, government agencies, and older organizations only process paper invoices. If they've told you "mail it," mail it.

Proof of delivery — When you need documentation that the invoice was sent and received, mailed invoices with Certified Mail create a paper trail that email can't match.

Collections escalation — If you're moving toward formal collection efforts, mailed invoices and notices create evidence that you properly billed the customer.

Contract requirement — Some contracts specify that invoices must be sent by mail to a particular address.

If the client accepts email and you don't need proof of delivery, email is faster and cheaper.

A complete invoice should have:

Your information

• Business name and address
• Contact information (phone, email)
• Tax ID or business registration number (if applicable)

Client information

• Company or individual name
• Billing address
• Account number (if you assign one)

Invoice details

• Invoice number (unique, sequential)
• Invoice date
• Due date (be specific: "Due January 31, 2026" not "Net 30")
• Purchase order number (if the client provided one)

Line items

• Description of goods/services
• Quantity
• Unit price
• Line total

Totals

• Subtotal
• Tax (if applicable)
• Total due
• Amount already paid (if partial payment received)
• Balance due

Payment instructions

• Accepted payment methods
• Where to send payment (address for checks, link for online payment)
• Bank details for wire transfer (if applicable)

Send invoices promptly — Mail invoices within a few days of completing work or delivering goods. Delays create cash flow problems.

Keep copies — Keep a copy of every invoice you send. If you end up in collections or court, you'll need it.

Match addresses — Use the billing address the client provided. If you're not sure, confirm before mailing.

Include a return envelope — For clients who pay by check, a return envelope (pre-addressed, not necessarily pre-stamped) increases the chance of timely payment.

Number invoices sequentially — Makes tracking easier and looks professional. Gaps in numbering can look suspicious if records are audited.

If an invoice goes unpaid, escalate with increasingly formal notices:

First reminder (7–14 days past due)
A friendly note: "This invoice is past due. Please remit payment or contact us if there's an issue."

Second notice (30 days past due)
More direct: "Your account is 30 days past due. Please pay immediately to avoid further action."

Final demand (60+ days past due)
Formal final notice before collections or legal action. Learn about final demand letters

Each notice creates evidence of your collection efforts.

For most routine invoices, regular First Class mail is fine. Use Certified Mail when:

• You're sending a past-due notice
• You need proof the invoice was delivered (for dispute purposes)
• You're building a paper trail for potential collections
• The client has claimed they "never received" invoices before

Certified Mail with Electronic Return Receipt provides tracking and signature confirmation.

1. Export your invoice as PDF — From QuickBooks, FreshBooks, Excel, or any invoicing software
2. Upload to PostalForm — We show a preview
3. Enter addresses — Your business address and the client's billing address
4. Choose delivery options — First Class for routine invoices, Certified Mail for past-due notices
5. Checkout — We print and mail via USPS

For significant invoices or new clients, consider adding a brief cover letter:

[Date]

Dear [Client Name],

Please find enclosed Invoice #[number] for $[amount], due [date].

If you have any questions about this invoice, please contact me at [phone/email].

Thank you for your business.

Sincerely,
[Your name]

The cover letter goes first in the PDF, invoice pages follow.

Upload your invoice PDF and we'll print and mail it for you.

Mail my invoice