Service Invoice Template

Each labor row is Hours × Rate; each parts row is Qty × Unit price. The two sections sum into the Subtotal. Tax applies only to the lines you flag taxable — every parts row has its own Taxable? checkbox, and the whole labor section is taxed (or not) by the single Tax labor? toggle:

subtotal     = Σ (hours × rate) + Σ (qty × unit price)
taxable base = (tax labor? Σ labor : 0) + Σ taxable parts
tax          = rate × taxable base, after any discount is applied to those lines
total        = subtotal − discount + tax + trip charge
balance due  = total − amount paid

A discount is applied to the subtotal before tax, and it reduces the taxable base proportionally. For example, a single $200 taxable part with a 10% tax rate and a 20% discount: the discount drops the taxable base from $200 to $160, so tax is 0.10 × 160 = $16.00, not $20.00, and the total is (200 − 40) + 16 = $176.00.

Money is rounded to 2 decimals for display. The default tax rate is blank — enter your own; this tool never assumes a jurisdiction. This is a billing document, not a tax filing or an accounting record: verify sales-tax rates and rules for your area before sending.

The workbook is one stop in a longer billing chain. The labor rate you type into the rate column should be the one you worked out in the service hourly rate calculator, not a number you carried over from a competitor, and a fully loaded cost behind it comes from the labor burden rate calculator. When you want a quick printable bill rather than an editable spreadsheet, the invoice generator produces the same document in the browser. Set the due date against the net 30 payment terms you actually agreed, and when that date passes, the late fee calculator works out a defensible charge while the past due invoice letter template gives you the reminder, second notice and final notice to send with it.