SaaS Invoice Template: Subscriptions, Seats and Proration

Quick answer: A SaaS invoice template bills a customer for subscription software. It shows the plan, billing period, number of seats or licenses, unit price, metered usage and overages, proration for mid-cycle changes, discounts, sales tax or VAT by location, the total, and whether it was auto-charged or is due by a date under payment terms.

Most subscription billing platforms generate invoices automatically, but small SaaS companies, agencies reselling software and founders invoicing their first enterprise customer often need to build invoices by hand. Even with automation, you need to know what a correct SaaS invoice contains. This guide covers subscriptions, seats, usage, proration, annual contracts, sales tax on SaaS and a fully worked example.

What is a SaaS subscription invoice?

A SaaS invoice is a recurring bill for access to software delivered online. Unlike a one-time sale, it covers a service period (a month, quarter or year), and the amount can change each period as seats, plan tier or usage change. It follows the logic of a recurring invoice, with extra lines for metered usage and mid-period adjustments.

Common SaaS pricing models and how they appear on invoices:

Model	Invoice line	Billed
Flat rate	Plan name, period, price	In advance
Per seat	Seats x price per seat	In advance, true-up for adds
Tiered	Tier name and its price	In advance
Usage-based	Units used x unit price	In arrears
Hybrid	Base fee plus included units plus overage	Base in advance, overage in arrears

For a deeper look at metered pricing, see our usage-based billing invoice guide.

What to include on a SaaS invoice

• Seller details: legal company name, address, tax registration numbers (sales tax permits, VAT number if registered).
• Customer details: legal name, billing address, customer VAT number for EU B2B, PO number if required.
• Invoice number, invoice date and due date, or "paid" with date and payment method.
• Service period for each line (for example Nov 1 to Nov 30, 2026).
• Plan and quantity: plan name, seats, unit price.
• Usage: included units, used units, overage units, overage rate.
• Proration lines with the dates covered.
• Discounts and credits (annual discount, coupon, prior credit).
• Tax by jurisdiction and rate, or exemption/reverse charge note.
• Total, amount paid and amount due.

Number invoices sequentially, even when your payment processor creates its own IDs; the invoice number generator and our numbering guide help.

How proration works (with the math)

Proration adjusts charges when a customer changes plan or seats partway through a period. The common daily method:

1. Daily rate = period price divided by days in the period.
2. Credit for unused time on the old plan = old daily rate x days remaining.
3. Charge for remaining time on the new plan = new daily rate x days remaining.
4. Net proration = charge minus credit.

Example: a customer on 10 seats at $15 per seat per month ($150) adds 5 seats on November 21 in a 30-day November billing period. Days remaining including the 21st: 10. Charge for 5 extra seats = 5 x $15 x 10/30 = $25.00. On the next invoice you bill 15 seats for December plus the $25.00 proration line. Our prorated invoice guide covers other methods, such as proration by month or by the second.

Example SaaS invoice (seats, usage and proration)

Invoice LB-2026-12-0381 | Ledgerbird Inc., Wilmington, DE | Invoice date: December 1, 2026 | Due: December 31, 2026 (net 30)
Customer: Harbor Freight Brokers LLC, Seattle, WA | PO: HFB-2026-55

Description	Period	Qty	Unit price	Amount
Team plan, per seat	Dec 1 to Dec 31, 2026	15	$15.00	$225.00
Proration: 5 seats added Nov 21	Nov 21 to Nov 30, 2026	5	$5.00	$25.00
API calls overage (100,000 included; 148,000 used)	Nov 1 to Nov 30, 2026	48 (per 1,000)	$0.40	$19.20
Additional storage (50 GB included; 72 GB used)	Nov 1 to Nov 30, 2026	22 GB	$0.10	$2.20
Subtotal				$271.40
Washington sales tax, Seattle, 10.35% (illustrative; verify current rate)				$28.09
Total due				$299.49

The base subscription is billed in advance (December), while proration and usage are billed in arrears (November). Each line states its own service period, so the customer can reconcile it against their usage dashboard. Washington treats many digital services as taxable, but confirm the current local rate with the Washington Department of Revenue lookup or our sales tax calculator.

Sales tax and VAT on SaaS

United States

SaaS taxability is set state by state, and it changes often. Several states generally tax SaaS (for example New York, Washington and Pennsylvania), Texas taxes it as a data processing service on 80% of the charge, and many states do not tax it at all. Since the 2018 Wayfair decision, remote sellers can have economic nexus based on sales into a state, even without staff there. Read our guide to sales tax nexus and the overview of sales tax on services by state, and verify current rules with each state's revenue department.

EU, UK and other VAT countries

SaaS is an electronically supplied service for VAT purposes. For EU business customers, VAT is usually handled by the customer under the reverse charge: show their VAT number and a reverse charge statement. For consumers, VAT is due at the customer's country rate; non-EU sellers can register for the One Stop Shop. See the EU VAT One Stop Shop guide and the European Commission's OSS portal.

This is general information, not tax advice.

Annual contracts, deferred revenue and enterprise invoicing

Annual plans paid upfront are attractive for cash flow, but under accrual accounting (ASC 606) you recognize the revenue over the subscription term, not on the invoice date. A $12,000 annual invoice is deferred revenue that becomes $1,000 of revenue each month. Read revenue recognition under ASC 606 and deferred vs accrued revenue for the accounting side.

Enterprise customers often require:

• An order form or MSA reference and PO number on every invoice
• Payment by ACH or wire on net 30 or net 45 terms
• Invoices submitted through a supplier portal
• A W-9 (US) and a security questionnaire before the first payment

How to invoice SaaS customers step by step

1. Define billing rules: period, advance vs arrears, proration method, overage rates.
2. Capture tax data at signup: billing address, VAT number, exemption certificates.
3. Close usage at period end and export the metered totals.
4. Build the invoice with base, proration, usage, discounts and tax lines. For manual invoices, the free invoice generator works well.
5. Charge or send: auto-charge cards and email a paid invoice; send open invoices with due dates for invoice-paying customers.
6. Run dunning on failures; see recurring payments for small businesses.

Discounts, credits and refunds on SaaS invoices

Subscription businesses issue a lot of adjustments. Show each one explicitly rather than editing the price, so revenue reports and customer records stay accurate.

• Annual prepay discount: list the full price, then a discount line (for example "Annual plan discount, 2 months free: -$300.00").
• Coupons and promotions: name the coupon and its duration ("LAUNCH20, 20% off first 3 months").
• Service credits: for SLA breaches or outages, add a credit line referencing the incident date and the SLA clause.
• Downgrade credits: carry forward as a credit balance applied to the next invoice.
• Refunds: issue a credit note against the original invoice instead of deleting or editing it.

Worked example: upgrade mid-cycle on a monthly plan

A customer on the $49 per month Starter plan upgrades to the $99 per month Growth plan on day 11 of a 30-day billing period. Twenty days remain, including the upgrade day.

Step	Calculation	Amount
Credit for unused Starter time	$49 x 20/30	-$32.67
Charge for remaining Growth time	$99 x 20/30	$66.00
Net proration charged now		$33.33

Many billing systems invoice this immediately; others add it to the next regular invoice. Either way, show both the credit and the charge with their date ranges. If you only show the net $33.33, support will get a ticket asking where it came from.

Common SaaS invoicing mistakes

• No service period on lines, so customers cannot tell what they paid for.
• Unexplained proration amounts. Show the dates.
• Ignoring sales tax nexus as revenue grows.
• Missing VAT numbers on EU B2B reverse charge invoices.
• Booking annual payments as immediate revenue.
• Sending invoices with card-on-file customers marked as unpaid, which creates double payments.

SaaS invoice checklist

• Legal names, addresses and tax IDs for both parties are correct.
• The invoice number is unique and sequential across all billing channels.
• Each line shows its own service period.
• Seat counts match the account's active users at the billing date.
• Usage lines show included, used and overage units with the rate.
• Proration lines show dates, credits and charges separately.
• Discounts and coupons are listed as their own lines.
• Tax is calculated for the customer's location, or an exemption or reverse charge note is shown.
• Status is clear: paid (with method and date) or due (with date and payment instructions).
• PO number and order form reference are included for enterprise customers.

If you start by sending invoices manually, keep a simple spreadsheet of customers, plans, seat counts and renewal dates. When you outgrow it, a dedicated billing system or the Stripe invoicing setup can automate the same structure.

Build your SaaS invoice

A SaaS invoice template that separates subscription, proration and usage lines, dates each one, and applies the right tax will survive any customer's accounts payable review. For manual or enterprise invoices, use our free invoice generator: no sign-up, the PDF is built in your browser, and you can download it and send it straight to the customer's billing contact.