Glossary of invoicing and business terms

What is an ACH payment? Batch bank-to-bank transfers in the U.S. Covers credits, debits, timing versus wires and cards, risk controls, and net 30 invoices.

What an EIN is, who needs a federal tax ID, how it differs from an SSN or ITIN, how to apply for free with the IRS, and where it appears on invoices.

What Form W-9 is, who completes it, how payers use it for 1099s, 24% backup withholding when TIN rules fail, four-year IRS retention guidance, and FAQs.

Invoice vs quote vs estimate in 2026: fixed price vs range vs payment request. When to use each, comparison table, workflow, checklists, and FAQs.

Net 30 means full payment is due within 30 calendar days of the invoice date unless your contract says otherwise. Covers 2/10 net 30, net 15 vs net 60, FAQs.

Retainage holds back part of each approved progress draw until closeout. Compare deposits, net terms, pay apps, waivers, release rules, and typical AR mistakes.

What is a retainer fee? It buys reserved capacity for a period through recurring invoices. Compare hourly vs fixed fees, deposits, net 30, rollover FAQs.

A credit note lowers an open invoice balance after returns, price fixes, or discounts. Compare memos, debit notes, revised invoices, and U.S. checklists.

What a pro forma invoice is for U.S. sellers, how import rules use it, how it differs from quotes and final invoices, and checklists to avoid payment confusion.

A purchase order (PO) is buyer-issued authorization to buy goods or services at agreed prices. Learn PO numbers, invoice matching, blanket POs, and mistakes.

Work orders align crews and billing before you invoice. Compare them with POs and invoices, link net terms, and use checklists and FAQs for US small businesses.

Accounts receivable (AR) is money owed from billed sales on credit. Compare AR vs AP, aging, net 30 due dates, collections habits, and common billing mistakes.

Cost-plus pricing adds an agreed markup to documented costs. Compare fixed price and T&M, see invoice lines, net 30 timing, and FAQs for US service businesses.

Invoice factoring converts invoices to cash via a factor. Compare recourse, notices, and fees with invoice financing, U.S. checklists, FAQs, and net 30 context.

Time and materials billing pays documented labor at agreed rates plus materials as work progresses. Compare fixed price, caps, invoices, and FAQs.