Quotation vs Invoice: What's the Difference?

The Simple Distinction

A quotation (or quote) is sent before work begins. It says: "Here is what I propose to do and what it will cost."

An invoice is sent after work is completed. It says: "Here is what I did. Please pay."

One is an offer. The other is a payment demand.

What Is a Quotation?

A quotation is a formal price offer from a seller to a potential buyer. It sets out:

What goods or services are being offered

The price for each item or service

How long the quote is valid (e.g. "valid for 30 days")

Any terms and conditions that apply

A quotation is not a guarantee of payment. The client may accept it, decline it, negotiate it, or ignore it. Only when the client accepts the quotation does it create a commitment — typically the start of a contract.

When to use a quotation:

Before starting any significant project

When a client asks "how much will this cost?"

For competitive tendering or formal purchasing processes

When you want a clear written record of what was agreed before work begins

What Is an Invoice?

An invoice is a document requesting payment for goods or services that have been delivered. It records:

What was provided

The agreed price

When payment is due

How to pay

Unlike a quotation, an invoice creates a legal obligation to pay. It is an accounts receivable for the seller and an accounts payable for the buyer.

When to use an invoice:

Immediately after delivering a service or product

When reaching a billing milestone on a longer project

On a monthly basis for ongoing services

Key Differences

| | Quotation | Invoice |

|---|---|---|

| Sent | Before work begins | After work is completed |

| Purpose | Offer a price | Request payment |

| Creates obligation | No (until accepted) | Yes |

| Recorded in accounts | No | Yes (as receivable) |

| Numbered | Quote number | Invoice number |

| Due date | None | Yes |

The Workflow: Quote → Invoice

The standard sales workflow is:

Client enquires about a job

You send a quotation with your price

Client accepts the quotation

You do the work

You send an invoice referencing the quotation

Client pays the invoice

The invoice should reference the quotation ("As per quotation Q-2025-044") so both documents are linked. If the client ever queries the amount, you can point to the quote they accepted.

What About Estimates?

An estimate is a rough, non-binding approximation of cost. It's used when the exact scope isn't clear enough for a firm quotation. An estimate might say "approximately $2,000–2,500 depending on final scope."

An estimate is less formal than a quotation. A quotation is a fixed price offer. An invoice is a payment demand. They sit in that order: estimate → quotation → invoice.

Converting Quotes to Invoices

In Quotation Expert, accepted quotations convert to invoices with one click. All line items, quantities, prices, and client details carry over — no re-entry. The invoice is automatically assigned the next sequential invoice number and linked back to the original quotation for a complete paper trail.

This workflow is the foundation of professional B2B selling: propose cleanly, invoice cleanly, get paid cleanly.