Tax Invoice Generator: a PDF with the tax percent you enter

The tax line on a bill should match the percent the form, the contract, or your accountant already named. You type that percent into this invoice, the total updates in front of you, and the PDF comes from the same preview. The form lives in the browser. Each line is a quantity times a price, and those lines add up to the subtotal. A discount, when you enter one, is a percent of that subtotal. Tax is a percent of the amount left after the discount. The grand total is the after-discount amount plus that tax. If the subtotal is 100, a 10 percent discount is 10, the amount after the discount is 90, and a 20 percent tax on 90 is 18, so the total is 108. Those figures are only an illustration of the arithmetic. The percents that belong on your bill are the ones you were asked to use. The tax field accepts the number you type, from 0 upward, including a decimal such as the rate on your paperwork. The page uses that number. It does not look up a country's VAT rate, GST rate, or sales-tax table. If the rate changed last month, the current figure has to come from you. The discount field works the same way: a percent you supply, applied to the subtotal before tax is calculated. The invoice number starts as INV- followed by the last six digits of the timestamp, and you can replace it with your own series. The date starts as today. Currencies are USD, EUR, GBP, BDT, INR, CAD, and AUD, so the symbol matches the code you pick. Add your business details, the customer, and the lines. When the preview reads the way you want the recipient to read it, download the PDF from that preview. Read the PDF once before you send it. Check the tax percent, the discount, and the total against the numbers you meant. Keep a copy of the file. If a price changes later, edit the form and download again, because the PDF is a snapshot of the preview at that moment.