If you have been running a small business in Sri Lanka for any length of time, you have probably been in this situation: a client asks you to send an invoice, but the work has not even started yet. Or you send a quotation after completing the job and wonder why the client takes so long to pay.
It sounds like a small thing, but sending the wrong document at the wrong time causes real confusion — and sometimes, real money problems. A lot of small business owners in Sri Lanka use these two words interchangeably, and that leads to misunderstandings about what has been agreed and what is owed.
In this article, we will clear that up once and for all. By the end, you will know exactly what a quotation is, what an invoice is, when to use each one, and how to make sure your clients understand the difference too.
The Short Answer
Here is the simplest way to remember it:
- A quotation comes before the work. It proposes a price.
- An invoice comes after the work. It requests payment.
That is really the core difference. But there is a lot more to each document, and getting the details right matters — especially when things go wrong with a client.
The Correct Business Document Flow
What Is a Quotation?
A quotation is a formal document you send to a potential client before any work begins. It tells them what you will provide, how much it will cost, and any conditions attached to that price — such as how long the quote is valid and what your payment terms are.
Think of it as a written offer. The client looks at your quotation and decides whether to accept it or not. If they accept, you both agree on the price and scope of work. If they decline or negotiate, you can revise it. Nothing is owed at this stage — the quote is just a proposal.
Key characteristics of a quotation
- Sent before work starts
- States a proposed price — not yet a confirmed charge
- Includes a validity period (usually 14–30 days)
- Can be revised or updated before the client approves
- No payment is due when a quotation is sent
- Becomes binding only when the client formally accepts it
A printing shop in Kandy gets a call from a client asking for the cost of 500 business cards. The shop owner sends a quotation: "500 full-colour double-sided business cards — Rs. 4,500. Valid until 20 December 2024." The client sees it, agrees, and orders. The printing begins. This is how it should work.
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An invoice is a formal request for payment. You send it after the work is done — or at agreed milestones during a project. It is essentially a bill that tells the client exactly what you delivered and how much they owe you.
Unlike a quotation, an invoice is not a proposal. The work has already been completed (or a milestone reached), and the invoice is the document that triggers the payment process. It should match the original quotation — unless there were agreed changes during the project.
Key characteristics of an invoice
- Sent after work is completed or at a milestone
- States a definite amount that is owed and payable
- Includes a payment due date (e.g., within 14 days)
- Has a unique invoice number for your accounting records
- Cannot be easily revised once sent — it is a formal demand for payment
- Forms part of your financial records and may be needed for tax purposes
Good to know: In Sri Lanka, invoices are important accounting documents. If your business is VAT-registered, your invoices must clearly show the VAT amount and your VAT registration number. Keep copies of all invoices for at least five years.
Side-by-Side Comparison
Here is a clear breakdown of how the two documents differ across all the key areas:
| Feature | Quotation | Invoice |
|---|---|---|
| When sent | Before work starts | After work is completed |
| Purpose | Propose a price for approval | Request payment for work done |
| Is payment due? | No — it's a proposal only | Yes — payment is required |
| Can be changed? | Yes, until client approves | No — it's a formal charge |
| Validity period | Yes (usually 14–30 days) | No — but has a payment due date |
| Reference number | Quotation number (QT-001) | Invoice number (INV-001) |
| Used for tax/accounting | Not typically | Yes — essential for VAT records |
| Legal standing | Binding once accepted by client | Legally enforceable debt document |
When to Use a Quotation vs an Invoice
Now that you know the difference, here are some practical scenarios to help you decide which document to send and when.
📋 Send a Quotation When…
- A client asks "how much will it cost?"
- You are bidding for a project or contract
- Work has not yet started
- You want to lock in a price before materials are purchased
- The client needs to get approval from a manager before committing
- You are offering a special or limited-time price
🧾 Send an Invoice When…
- The work is finished or a stage is complete
- The client has already approved your quotation
- You are requesting your advance payment amount
- A monthly retainer payment is due
- You have delivered goods to the client
- You need a record for your accounting or tax filing
Your invoice should reference the original quotation number. For example: "This invoice is for work approved under Quotation QT-2024-015." This creates a clear paper trail and reduces payment disputes significantly.
Common Mistakes Sri Lankan Businesses Make with These Documents
Sending an invoice before getting approval
This happens quite often. A business owner quotes a price verbally, does the work, then sends an invoice — but the client never formally agreed to the price. Now there is a dispute. Always get written approval of your quotation before you start work.
Using one document for both purposes
Some businesses send a single document labelled "Quotation/Invoice" and use it for everything. While this might seem convenient, it creates confusion — the client is unsure whether they are being asked to approve something or to pay something. Keep them separate.
Changing the invoice amount from the quotation
If your final invoice is different from the approved quotation, you need to explain why — in writing, before you send the invoice. Surprising a client with a higher amount than what they agreed to is one of the fastest ways to lose a customer and your professional reputation.
Not keeping copies
Both quotations and invoices are important business records. Keep digital or physical copies of all of them — especially invoices — because you may need them for your tax returns, for resolving payment disputes, or for proving the terms of an agreement.
⚠️ Important: Never send an invoice for work you have not done. An invoice is a formal claim for payment. Sending one before delivering the agreed product or service can create legal and financial problems for your business.
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Not always. For very small or casual transactions, many businesses in Sri Lanka skip the quotation and just do the work and invoice. That is fine for trusted, repeat clients — but for new clients, or any job over a few thousand rupees, a proper quotation first is always the smarter approach.
For larger projects — construction work, IT development, event planning, or ongoing services — both documents are important. The quotation sets the expectations; the invoice confirms what was delivered and what is owed.
Conclusion
The difference between a quotation and an invoice is straightforward once you understand the flow: quotation first, work second, invoice third. Keeping these two documents separate and clear protects you legally, helps you get paid faster, and makes your business look far more professional to clients.
The good news is that creating both does not have to be complicated or time-consuming. With the right tools, you can have a professional quotation or invoice ready in a couple of minutes — and that alone will set you apart from most small businesses in Sri Lanka.