SaaS Invoice Template

To generate an invoice, go to the Invoice sheet and enter the invoice number, select the customer from the dropdown, and confirm the billing period. Fill in the applicable line items — subscription fee, seat count if seat-based, usage overages pulled from the Usage Log, and any professional services or one-time charges for that period. The totals block calculates subtotal, discount, and tax automatically. Export to PDF and send to the billing contact listed in the Customer List. For monthly recurring customers, most of the line items stay the same — it's usually just the usage overage row that changes.

The SaaS billing structure that works is one that separates line item types rather than mixing them into a single undifferentiated table. Subscription fees are fixed and predictable; usage overages require calculation from a separate log each period; professional services may be hourly or milestone-based. Keeping these in distinct sections with their own subtotals makes the invoice readable for the customer and auditable for your own finance team. It also makes disputes easier to resolve — when a customer questions an overage charge, you can reference the Usage Log and show exactly which billing period and usage figure the charge is based on.