What you need before you start
Start with the commercial agreement and the rules that apply to the transaction. The fields below are common, but a tax invoice, public-sector invoice or structured e-invoice may need additional identifiers or a different delivery channel.
- Supplier details
- The legal or trading name, address and contact details, plus registration and tax identifiers when the applicable rules require them.
- Customer details
- The customer’s correct legal name, billing address and any purchase-order, buyer, tax or routing identifier they asked you to use.
- The supply
- Clear descriptions, quantities, units, prices, discounts and the supply or service period needed to explain each charge.
- Tax treatment
- The rate, exemption, zero-rate or reverse-charge treatment you have independently confirmed for this transaction.
- Dates and terms
- The issue and supply dates, the agreed due date, currency, payment terms and any contract reference.
- Delivery and payment details
- The accepted invoice format and channel, verified bank details or payment URL, and the correct recipient.
How to make an invoice in seven steps
Use these seven steps as a working sequence, then compare the draft with the contract, customer instructions and local invoicing rules.
- 1. Choose the document and channel
- Confirm whether the customer accepts a PDF or requires a portal, structured e-invoice or tax-authority submission.
- 2. Identify the parties
- Enter the supplier and customer names, addresses and identifiers required for this transaction.
- 3. Add a reference and dates
- Use a unique invoice identifier, a sequential series where required, and the relevant issue, supply and due dates.
- 4. Describe each charge
- List the goods or services with enough detail to match the agreement, including quantity, unit price and discounts where relevant.
- 5. Calculate tax and totals
- Check each line, subtotal, tax category, rate, tax amount, rounding and final amount in the stated currency.
- 6. Add agreed payment terms
- State the due date and verified payment instructions. Add interest, fees or retention terms only when the agreement and law support them.
- 7. Validate, send and retain
- Review the identifiers and arithmetic, deliver through the accepted channel, and retain the invoice and supporting records for the required period.
Common invoice fields, and what to verify
Most invoices identify the document, supplier, customer, transaction, dates, amounts, currency and payment terms. Tax invoices may also require registration numbers, a sequential number, the supply date, taxable amounts by category, rates, tax amounts and prescribed notes. Public-sector and cross-border invoices can require buyer references, electronic addresses or structured fields that do not appear on a basic PDF.
Do not treat a generic checklist as proof of legal validity or the customer’s right to deduct tax. Confirm the rules for the supplier’s status, place of supply, customer type and invoice value. The UK checklist and EU VAT Directive in the sources illustrate how official requirements differ even across familiar invoice fields.
How to calculate totals and tax
For each line, multiply quantity by unit price, apply any line discount and check the result. Add the lines to the net subtotal, calculate tax using the confirmed category and rate, then show the gross total and any amount already paid. Follow the applicable rounding rule and keep all amounts in the stated currency.
Software can perform arithmetic after you enter a rate, but it cannot establish the legal treatment from a short form. Registration, location, customer status, product or service and special schemes can all change the result. Do not assume that a cross-border sale is automatically reverse charge, exempt or zero-rated. Verify the treatment and any required wording before issue.
Invoice numbers and dates
Use an identifier that is unique within the series and period required by your rules. Some tax systems require a sequential number based on one or more series, but there is no universal no-gaps rule. If you void, cancel or correct a document, preserve the required audit trail instead of reassigning an identifier in a way that obscures the record.
The dates you need can include the issue date, supply or service date, payment due date and tax-point date. Derive the due date from the agreement and show a calendar date when practical. Do not change an issue or supply date merely to shift reporting into another period.
How to send your invoice and get paid
A PDF is common, but it is not immutable and it does not replace a required structured e-invoice, customer portal or tax-authority channel. Send the format the recipient and jurisdiction accept. Check the recipient before exposing personal data or bank details, and retain the original invoice plus evidence of delivery and later corrections.
Use verified payment instructions and state the due date clearly. If the invoice becomes overdue, follow the agreed reminder process and the local rules on interest, recovery fees and debt collection. Confirm a change to previously agreed bank details through a trusted channel before relying on it.
Common mistakes to avoid
Review these points before issue. Each can make an invoice harder to accept, reconcile, report, or pay.
- A duplicate or unexplained reference
- Keep identifiers unique within the required series and preserve the audit trail for cancelled, voided, and corrected documents.
- The wrong party or routing details
- A trading name may not be the customer’s legal billing entity, and some buyers require a purchase order or electronic address.
- Unverified tax treatment
- Registration alone does not determine the rate, exemption or reverse charge. Confirm the specific transaction.
- Vague line descriptions
- Describe the supplied goods, service period or milestone well enough to match the agreement and support review.
- Unverified payment instructions
- Check bank details and payment URLs before issue, especially when instructions have recently changed.
- Using PDF when structured data is required
- A readable PDF can still fail a customer or authority mandate for a structured e-invoice or portal submission.
Frequently asked questions
Do I need software to make an invoice?
Not always. A word processor, spreadsheet or generator may be enough when the recipient and jurisdiction accept that format. Software helps with arithmetic, numbering and records, but it does not decide the correct tax treatment. Some transactions require structured e-invoicing or an authority channel.
What information must an invoice include?
There is no universal minimum. Common fields identify the supplier, customer, invoice, dates, goods or services, currency and amounts. Tax invoices can require registration numbers, a sequential number, taxable amounts, rates, tax amounts and prescribed notes. Check the rules for the transaction and any customer routing requirements.
How should I number my invoices?
Use an identifier that is unique within the series and period required by your rules. Some systems require a sequential number from one or more series, such as 2026-001 and 2026-002, but do not assume every jurisdiction has the same no-gaps rule. Preserve the required trail for voided, cancelled, and corrected invoices.
Do I have to charge VAT or sales tax?
It depends on registration, the supplier and customer locations, customer status, what was supplied and any special scheme. Do not charge tax, apply a reverse charge or show a registration number based only on a generic example. Confirm the treatment for the transaction.
Can I make an invoice for free?
Yes. The generator on this page can create a PDF draft without an account, card or watermark. You remain responsible for checking its identifiers, tax treatment, required fields and accepted delivery format before issue.