Gather information before picking a template
Use the accepted quote or agreement, not memory. Verify the customer, address, actual delivery and any deposits. An attractive document cannot fix the wrong identity or quantity. Prepare a clearly marked draft until checks are complete.
Compare each draft line with the quote and flag differences to explain.
Check the details required for your situation
The official guide distinguishes general details from situation-specific requirements. Check identities, dates, numbering, itemisation, amounts and payment. VAT and exemption wording depend on your regime: do not copy wording from another invoice. Also check the electronic invoicing schedule applicable to your business.
Open the source and check applicable details one by one. This tutorial does not certify compliance.
Track payment without confusing dates
After approval, keep the issued version and evidence of sending. Track issue date, due date and confirmed payment separately. Before following up, check that payment has not already arrived and that the recipient is correct. Draft a factual message with the reference and outstanding amount. Sent does not mean paid.
Create four columns: reference, due date, outstanding amount, last contact.
Arithmetic check, excluding VAT and other details: three hours at €40 equals €120. If your draft says €140, correct it before issuing. This is not a compliant invoice template.
An invoice needs to be checkable, not just presentable.