📘 Invoicing Glossary

The plain-English invoicing glossary

Clear, jargon-free definitions of the invoicing and billing terms freelancers and small businesses actually run into, from "what is an invoice" to Net 30, proforma invoices, and past-due balances.

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Core concepts

Recurring Invoice

A recurring invoice is an invoice that is automatically generated and sent on a set schedule for ongoing services.

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Retainer

A retainer is an upfront fee a client pays to reserve ongoing access to your services, either drawn down against work or as a recurring fixed fee.

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Invoice

An invoice is a document a seller sends to a buyer that itemizes goods or services provided and requests payment by a stated due date.

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Invoice number

An invoice number is a unique identifier assigned to each invoice so it can be tracked, referenced, and reconciled in accounting records.

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Invoice vs. receipt

An invoice is a request for payment sent before money changes hands, while a receipt is proof of payment issued after the buyer has paid.

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Purchase order

A purchase order (PO) is a document a buyer sends to a seller to officially authorize and commit to a purchase, listing the items, quantities, and agreed prices.

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Statement of account

A statement of account is a summary document that lists all invoices, payments, and the outstanding balance for a customer over a period of time.

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Itemized invoice

An itemized invoice lists each product or service as a separate line, with quantity, rate, and amount, rather than charging a single lump sum.

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Invoice vs. quote

A quote is an estimate of cost given to a customer before work begins, while an invoice is a request for payment issued once the work is agreed or completed.

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Purchase order number

A purchase order number (PO number) is the unique identifier assigned to a purchase order, used to track the order and match it to the invoice that follows.

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Invoice types

Getting paid

Invoice payment

An invoice payment is the funds a buyer sends to a seller to settle the amount owed on an invoice, by or before its due date.

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Payment terms

Payment terms are the conditions on an invoice that state when payment is due and how it should be made, for example "Net 30" or "Due on receipt."

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Net 30

Net 30 is a payment term that means the full invoice balance is due within 30 days of the invoice date.

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Due on receipt

"Due on receipt" is a payment term meaning the client is expected to pay the invoice immediately upon receiving it, rather than within a set number of days.

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Past-due invoice

A past-due invoice is an invoice that has not been paid by its due date, making the balance overdue.

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Retainer fee

A retainer fee is an upfront payment a client makes to secure a provider’s availability or services, often drawn down against future work as it’s performed.

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Timesheet

A timesheet is a record of the hours a person works on tasks or projects over a period, used to bill clients accurately and to pay employees.

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Dunning

Dunning is the process of systematically communicating with customers to collect overdue payments, usually through a sequence of escalating reminders.

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Chargeback

A chargeback is a forced reversal of a card payment, initiated by the cardholder’s bank, that returns the funds to the customer and pulls them back from the merchant.

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ACH payment

An ACH payment is an electronic bank-to-bank transfer processed through the US Automated Clearing House network, commonly used to pay invoices and run payroll.

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Wire transfer

A wire transfer is an electronic, bank-to-bank transfer of funds, usually settled quickly and often used for large or international payments.

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Billing basics

Accounting

Payment terms

Taxes and business