Sales Orders: What to Include, How to Write One, and Common Mistakes

A sales order is the document you create when a customer commits to buying from you. It's not an invoice—it's the internal record that kicks off picking, packing, shipping, or service delivery. Getting the fields right and avoiding rookie mistakes saves you from shipping the wrong items, arguing about prices, or chasing payments. Here's exactly what you need to know.

What to Include in a Sales Order

Every sales order needs two layers of information: header details that identify the parties and line items that describe what's being sold. Here's the checklist:

Header fields:

• Your business name, address, phone, and email
• Customer's name, billing address, and shipping address (if different)
• Unique sales order number (sequential, like SO-001)
• Order date and requested delivery date
• Payment terms (e.g., Net 30, 2/10 Net 30, or due on receipt)
• Shipping method and expected delivery window

Line item fields:

• Item or service description (be specific—"Widget A, blue, 12-inch" not just "Widget")
• Quantity ordered
• Unit price
• Discounts (if any) per line or as a subtotal adjustment
• Line total (quantity × unit price minus discount)
• Subtotal, sales tax (with rate), shipping charges, and grand total

Optional but recommended:

• Purchase order number (if the customer uses one)
• Notes or special instructions (e.g., "Leave at loading dock")
• Your logo and terms and conditions

One concrete example: If you sell 50 units of "Ergonomic Office Chair – Black" at $199 each with a 10% volume discount, your line item shows: Qty 50, Unit Price $199, Discount 10%, Line Total $8,955. Then subtotal, 8% tax ($716.40), and grand total $9,671.40.

How to Write a Sales Order in 5 Steps

Step 1: Capture the customer's intent. Before you type anything, confirm what the customer wants—verbally, by email, or through a signed quote. Get the exact product codes, quantities, and agreed prices in writing.

Step 2: Fill in the header. Enter your info, the customer's details, and the order date. Assign a unique sales order number. If you're using accounting software, this usually auto-generates.

Step 3: Add line items one by one. For each product or service, write a clear description, quantity, and unit price. Double-check discounts. If you have 15 line items, list them all—don't group them into one vague line.

Step 4: Calculate totals and add tax. Sum the line totals, apply any subtotal discounts, calculate sales tax based on your jurisdiction's rate, and add shipping. Show the grand total clearly.

Step 5: Set terms and send. Write payment terms, expected delivery date, and any special instructions. Send a copy to the customer for approval before you start fulfilling. Keep the original for your records.

Common Mistakes That Cost You Money

Mixing up sales orders and invoices. A sales order is not a bill. If you send a sales order when the customer expects an invoice, they might ignore it. Worse, if you ship before the sales order is approved, you risk non-payment. Always get a signed or acknowledged sales order first.

Skipping item descriptions. Writing "Part #123" without a description forces your warehouse to guess. A picker might grab the wrong size, color, or version. Write "Part #123 – Steel Bolt, 3/8-inch, Zinc-Plated" every time.

Forgetting to include the customer's purchase order number. Many businesses require a PO number to process payment. Leave it off, and your invoice gets kicked back. Ask for it upfront.

Using vague payment terms. "Net 30" is clear. "Pay when you can" is not. Specify exact terms and put them on the sales order so there's no confusion later.

Not updating quantities or prices after customer changes. A customer calls to add 10 more units. You ship 60 but the sales order still says 50. Now your inventory is off and the invoice is wrong. Update the sales order before you fulfill.

Sales Order vs. Purchase Order vs. Invoice

These three documents get confused constantly. Here's the simple breakdown:

• Purchase order (PO): The customer sends this to you. It says "I want to buy this."
• Sales order (SO): You create this based on the PO or customer request. It says "I confirm I'll sell this to you."
• Invoice: You send this after delivery. It says "You owe me this amount."

Your sales order bridges the customer's request and your fulfillment. Get it right, and the invoice is easy. Get it wrong, and you're untangling shipping and billing errors for weeks.