Key takeaways
- Limited companies must show their registered details on letters, order forms and websites.
- EU VAT rules set the core contents of a full invoice; member states add national rules, and the UK has its own.
- Credit notes must clearly refer to the original invoice they amend.
- Quotations, purchase orders and written contracts are commercial records that prevent disputes, even where the law does not require them.
Company details on letters, order forms and websites
EU company law requires limited companies' letters and order forms, on paper or in any other medium, to state the register where the company is filed and its registration number, its legal form and the location of its registered office. Company websites must show at least the same particulars. In the UK, a limited company must show its registered number, registered office address, where it is registered and that it is a limited company on business letters, order forms and its website.
- Put these details in your letterhead and email signature so every letter and quotation carries them.
- If you mention share capital, state the paid-up capital, as both the EU and UK rules require.
- If you list directors' names on UK stationery, list all of them.
The core documents and what each one is for
| Document | Purpose | Key point to get right |
|---|---|---|
| Quotation | Offer scope and price before work starts | Validity date, exclusions and whether prices include VAT |
| Purchase order | Buyer's written approval to buy | Matches the accepted quote and names the billing entity |
| Invoice | Request payment for a supply | Sequential number, both parties, description, VAT where it applies |
| Credit note | Correct or reverse an invoice | Clear reference to the original invoice |
| Delivery note | Prove what was delivered | Quantities checked and signed on receipt |
| Receipt | Confirm money received | Amount, date, method and the invoice it settles |
| Service agreement or terms | Set out the working relationship | Scope, payment terms, liability and termination |
| Employment contract | Record employment terms | Written terms given within the legal deadline |
Invoices: EU rules, national rules and the UK
According to the European Commission, businesses across the EU follow one set of basic invoicing rules, with certain national rules added by member states. A full VAT invoice includes the issue date and a unique sequential number, both parties' full names and addresses, the customer's VAT number where the customer is liable for the tax, a description and quantity of the goods or services, the unit price excluding tax, the date of supply if different, and the VAT rate and amount. Simplified invoices carry less, and credit or debit notes must clearly refer to the original invoice.
Electronic invoices are equivalent to paper ones when the recipient accepts them, but public bodies must accept structured e-invoices, and several countries are introducing mandatory e-invoicing between businesses. A PDF made in an editor is not a structured e-invoice. The UK is outside the EU VAT system and follows HMRC's own invoice rules.
Check your member state's national provisions in the European Commission's Tax Information Communication database, and the UK rules on GOV.UK, before issuing invoices.
Contracts, employment terms and records
Written terms protect a small company far more than any template's design. Use a service agreement or terms and conditions for ongoing clients, and a non-disclosure agreement before sharing confidential plans. Employers must give employees written terms of employment within the deadline set by national law. Keep issued invoices, credit notes and the supporting quotes and purchase orders for as long as your tax authority requires.
- Set up your letterhead with the company's registered details once.
- Use the same numbering series for invoices, and never reuse a number.
- Agree payment terms in the quotation or contract, then repeat them on the invoice.
- Fix errors with a credit note that refers to the original invoice rather than editing a sent invoice.
- Store the full trail: quote, PO, delivery note, invoice, receipt.
DocMak helps you prepare professional business documents. It does not register your business with any government portal, verify your registration numbers or decide your tax treatment. Registration rules, portals and fees change: always follow the official portal and the buyer's own instructions. Free creation and downloads remain subject to the existing account and usage limits.
Frequently asked questions
What must a limited company show on its website?
Under EU company law, at least the register and registration number, legal form and registered office, plus paid-up capital if capital is mentioned. In the UK, the registered number, registered office address, place of registration and that it is a limited company.
Is a PDF invoice an e-invoice?
Not for structured e-invoicing purposes. Public bodies and an increasing number of countries require structured electronic invoices; check your country's current rules.
Do UK invoices follow EU VAT rules?
No. The UK follows its own VAT invoice rules published by HMRC on GOV.UK.
How do I correct an invoice I have already sent?
Issue a credit note that clearly refers to the original invoice, then a new invoice if needed, rather than changing the one already sent.
Official sources
Check these official pages for the latest requirements before filing or making a compliance decision.