Invoicing guide
How to Write an Invoice: A Step-by-Step Guide
Everything you need to put together a clear, professional invoice — what to include, how to number it, how to word your payment terms, and the mistakes that most often delay getting paid.
What is an invoice?
An invoice is a formal request for payment that you send to a client after (or sometimes before) delivering work or goods. It lists what was provided, how much it costs, and when payment is due. Unlike a receipt — which confirms payment already made — an invoice is what sets payment in motion.
What to include on every invoice
A complete invoice should always contain the following:
- Your business name, address, and contact details
- Your client's name and billing address
- A unique invoice number
- The invoice date and payment due date
- An itemized list of what you're billing for, with quantity and price per item
- Subtotal, any tax, any discount, and the final total due
- Your preferred payment method or instructions
- Payment terms (e.g. due on receipt, Net 15, Net 30)
Missing any of these is one of the most common reasons invoices get delayed — clients often hold off paying simply because something needed for their own records (like a tax breakdown or invoice number) isn't there.
Step-by-step: writing an invoice
1. Start with a clear invoice number
Use a consistent, sequential format — for example INV-2026-001, INV-2026-002, and so on. This makes it easy for both you and your client to track and reference the invoice later, especially for tax records.
2. Add your business and client details
Put your business information at the top, and your client's billing details clearly underneath. If you're invoicing a company rather than an individual, address it to the right department or contact where possible.
3. List what you're billing for
Break work down into individual line items rather than one lump sum where possible — for example, separate "Design" and "Development" rather than a single "Project work" line. This gives clients confidence in what they're paying for and reduces back-and-forth questions.
4. Calculate subtotal, tax, and total
Add up your line items for the subtotal, apply any tax that's relevant to your business and location, factor in any agreed discount, and clearly state the final total due. Double-check your math — arithmetic errors are one of the fastest ways to lose a client's trust in your invoicing.
5. State your payment terms clearly
Don't leave payment timing ambiguous. Common terms include:
| Term | Meaning |
|---|---|
| Due on receipt | Payment expected immediately upon receiving the invoice |
| Net 15 | Payment due within 15 days of the invoice date |
| Net 30 | Payment due within 30 days of the invoice date |
| 50% upfront | Half paid before work begins, remainder on completion |
6. Send it — and follow up if needed
Email is the standard way to deliver an invoice today, typically as a PDF attachment so formatting stays consistent regardless of the device it's opened on. If a due date passes without payment, a polite follow-up referencing the invoice number is usually enough to resolve it.
Common invoice mistakes to avoid
- No invoice number. Makes it hard for clients to reference and track internally, which can delay payment.
- Vague line items. "Services rendered" tells a client nothing — be specific about what was delivered.
- Missing due date. Without one, clients default to paying whenever is convenient for them, not you.
- Inconsistent formatting. Sending a differently-formatted invoice each time looks unprofessional and is harder for clients to process quickly.
- No payment instructions. Always state exactly how you want to be paid — bank transfer details, payment link, or otherwise.
Skip the manual formatting
MineInvo builds a clean, correctly-formatted invoice for you automatically — line items, tax, totals, and all — free, with no signup.
Create an invoice now →Frequently asked questions
An invoice is a request for payment sent before or after work is delivered. A receipt is proof of payment already received. You send an invoice to get paid; you issue a receipt to confirm you were.
It depends on your location, business structure, and what you're selling. Requirements vary widely by country and region, so check your local tax authority's rules for your specific situation.
Net 15 or Net 30 are the most common terms. Shorter terms improve cash flow but may not suit every client relationship — whatever you choose, state it clearly on the invoice itself.
In most places, yes — freelancers and sole proprietors can typically invoice under their own name without formal registration, though you may still need to report the income for tax purposes.