Resources
Invoice Resources
Guides and calculators covering the parts of invoicing that actually cause problems: what belongs on the document, how to number it, what payment terms mean, and how the arithmetic works.
What do these resources cover?
Five written guides on writing, numbering, dating and explaining invoices, plus three calculators for tax, discounts and due dates. Each one connects back to the invoice generator so you can apply it immediately.
Every page here exists because the question comes up while someone is in the middle of billing a client. They are written to be read in a few minutes and acted on the same day, not to be comprehensive for its own sake.
Invoicing guides
How to Write an Invoice
How to write an invoice that gets paid: the required details, the order they belong in, how to number and date it, how to set terms, and a full worked example.
Invoice Examples
Real filled-in invoice examples for hourly freelance work, a fixed-price project, a product sale with tax and shipping, and a contractor job with labour and materials.
Invoice Payment Terms Explained
What invoice payment terms mean and when to use each one: due on receipt, Net 7, Net 15, Net 30, Net 60, deposits, milestones, early-payment discounts and late fees.
Invoice Numbering Systems
How invoice numbering works, which formats are safe to use, why numbers must be sequential and unique, and how to handle restarts, credit notes and gaps.
Invoice vs Receipt
An invoice requests payment; a receipt confirms payment was made. Compare what each document contains, when to issue them, and how they are used in bookkeeping.
Invoice calculators
Small utilities that answer one question each, using the same calculation order as the invoice generator.
Invoice Tax Calculator
Calculate tax on an invoice line by line: subtotal, discount, tax rate, shipping and grand total. Shows the exact formula and calculation order used on your invoice.
Invoice Discount Calculator
Calculate a percentage or fixed discount on an invoice and see how it changes the taxable amount. Includes the discount-before-tax order and worked examples.
Invoice Due Date Calculator
Work out an invoice due date from the issue date and your payment terms — Net 7, Net 15, Net 30, Net 45, Net 60 or a custom number of days — with the date written out.
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