Fixed fee or percentage of revenue: what will billing cost you at scale?
Last updated: November 2026
Is a fixed fee cheaper than a percentage of revenue?
How billing platforms charge
Billing platforms use four main pricing models, and many combine two of them. What matters is what makes your bill grow.
| Model | What makes the bill grow | What to watch |
|---|---|---|
| Percentage of revenue | Every extra dollar you bill | What counts as "billed": one-off charges, usage, tax, refunds |
| Per transaction or per event | Every invoice, payment or usage event | Usage-heavy products send many events |
| Per user or seat | Every person who uses the system | Finance, support and engineering seats add up |
| Fixed fee | Nothing during the term: the fee is known in advance | Contract term, and what the fee does not cover |
What published percentage rates look like
Billing platforms that publish a percentage-of-revenue price list rates between 0.5% and 0.8% of billing volume, in the public pricing pages we reviewed in November 2026. Several add a monthly platform fee or a charge per usage event, and most of these pages offer custom pricing for larger volumes on request. These rates are for the billing software only. Payment processing is charged separately by your payment provider.
Ranges come from public pricing pages, checked on the date above. Prices change; check each provider's current page.
Calculate your break-even
Use your own figures. The calculation runs in your browser.
Result
| Year | Billed revenue | Percentage model | Fixed option | Difference |
|---|---|---|---|---|
| Year 1 | USD 25,000,000 | USD 175,000 | USD 120,000 | USD 55,000 |
| Year 2 | USD 25,000,000 | USD 175,000 | USD 120,000 | USD 55,000 |
| Year 3 | USD 25,000,000 | USD 175,000 | USD 120,000 | USD 55,000 |
| Total | USD 75,000,000 | USD 525,000 | USD 360,000 | USD 165,000 |
How it is calculated
Revenue in year n: R_n = R × (1 + g)^(n − 1) Percentage model, year n: P_n = R_n × p + 12 × m Fixed option, year n: F_n = F + O Difference, year n: D_n = P_n − F_n (positive = fixed fee costs less) Totals over N years: sum of P_n, F_n and D_n Break-even billed revenue: R* = (F + O − 12 × m) / p (when p > 0) Fixed fee as a share (year 1): F / R
R = revenue you bill per year, p = percentage rate, m = monthly platform fee, F = fixed annual fee, O = your annual cost to run a self-hosted system, g = yearly growth, N = years to compare. Amounts are rounded to the nearest dollar.
This is an estimate, not a price quote. It uses only the numbers you enter. They exclude payment processing fees, taxes, and the cost of hosting and running any software unless you enter it in the self-hosted cost field. Providers may use tiered rates, minimums, event charges or negotiated contracts: check their current pricing. Kill Bill open source is free. For Aviate, see the pricing page.
The break-even formula
Break-even billed revenue = fixed annual fee ÷ percentage rate.
With a fixed fee of USD 120,000 a year:
| Percentage rate | Break-even billed revenue per year |
|---|---|
| 0.5% | USD 24.0 million |
| 0.7% | USD 17.1 million |
| 0.8% | USD 15.0 million |
At a 0.7% rate, one year
| Revenue billed per year | Percentage fee (0.7%) | Fixed fee | Difference | Fixed fee as a share of revenue |
|---|---|---|---|---|
| USD 10 million | USD 70,000 | USD 120,000 | USD 50,000 more for the fixed fee | 1.20% |
| USD 25 million | USD 175,000 | USD 120,000 | USD 55,000 less for the fixed fee | 0.48% |
| USD 50 million | USD 350,000 | USD 120,000 | USD 230,000 less for the fixed fee | 0.24% |
| USD 100 million | USD 700,000 | USD 120,000 | USD 580,000 less for the fixed fee | 0.12% |
Growth makes the gap wider. At USD 25 million in year 1 and 20% growth a year, a 0.7% fee costs USD 637,000 over three years. The fixed fee costs USD 360,000.
What a fixed fee does not include
- Hosting and operations. With self-hosted software you run the servers, the database, backups, monitoring and upgrades. Budget for them; the calculator has a field for that cost.
- Payment processing. Card and bank fees go to your payment provider under either model. Kill Bill connects to your gateway through plugins and does not charge gateway fees.
- A contract term. Fixed fees usually come with a commitment. Check the term and how often you pay.
- Your team's time. A billing system needs people who understand your catalog, your invoices and your integrations, whoever hosts it.
When a percentage fee is the better deal
- You bill less than the break-even amount, and expect to for a while.
- You have no team to run a Java service and its database, and do not want one.
- You want the provider to run uptime, upgrades and security patches for you.
If that is you, a percentage-of-revenue platform may well cost less overall. The fixed fee starts to pay off when billed revenue is large or growing fast, and when you want the billing data and the code in your own infrastructure.
Questions to ask any billing vendor about price
- What counts as billing volume: one-off charges, usage, taxes, refunds, credit notes, zero-amount invoices?
- Is the rate tiered or degressive, and at which thresholds?
- Is there a monthly minimum or platform fee on top of the percentage?
- Are usage events, API calls or invoices charged separately?
- Does the price change when you add an entity, a currency or a region?
- What happens to the price at renewal?
- Are support response times included, or sold as an add-on?
- How do you export your data if you leave, and in what format?
Where Kill Bill and Aviate fit
Kill Bill is open source billing and payments software, free under the Apache 2.0 license and in production since 2010. You run it yourself, with community help only: no support and no SLA. Aviate is a distinct commercial product built on Kill Bill, with a fixed price: see the pricing page. Neither charges a percentage of revenue or a fee per transaction. Aviate runs in your infrastructure. Its Control Plane, sign-in and software distribution are hosted by Kill Bill and hold no billing data. Aviate includes Premium support, with an answer within 2 business days for critical production issues. You can evaluate it in a free sandbox hosted in Kill Bill's cloud.