For a question about a published invoice guide, email [email protected]. This is the site’s public contact address.
What to include
- The guide or page you are asking about, with its URL if possible.
- A short description of the field, calculation or check that is unclear.
- The spreadsheet or invoicing app you are using, if the question is about a table or formula.
What not to send
Do not send customer names, addresses, card numbers, bank account details, passwords or signed contracts. The site does not need those records to answer a general question about a guide.
What to expect
This is a small reference project, not a billing service or legal help desk. There is no contact form, ticket system or guaranteed response time. A reply does not create a lawyer, accountant or client relationship.
Start with How to Fill Out an Invoice or How to Check Invoice Calculations.