Software & digital3 min read
Best LLC for an API business: usage billing and service taxability
An API is sold to developers, billed by consumption and depended on in production. Each of those three facts creates an obligation that a normal software subscription does not.
The short answer
A single-member LLC while bootstrapping, a Delaware C-corp if raising. The specific work is in the contract — uptime, rate limits and liability caps — and in whether your service is taxed as software or as data processing.
Published
Selling an API is selling a dependency. Your customers build on you, which is excellent for retention and uncomfortable for liability, and it shapes the parts of the business that are worth structuring carefully.
The short answer
The entity choice is the ordinary software one — see the SaaS guide. What is genuinely different is below.
Usage billing is a credit decision
Post-paid consumption billing means you deliver first and invoice after. That is lending, in small amounts, to everyone who signs up.
- A runaway loop on a customer's side becomes your bad debt. Someone's misconfigured retry can generate a bill they will not pay, and you have already incurred the underlying cost.
- Set hard caps by default, with opt-out for customers who have earned it. Soft alerts are not a control.
- Prepaid credits move the risk, which is why so many API businesses use them.
- Revenue is recognised as consumed, not as sold. Prepaid credits are a liability until used — the same deferred-revenue discipline a subscription box needs.
Software or data processing?
States that tax software do not always tax services, and some reach services like data processing or information services that a plain software subscription would escape — occasionally at a partial rate. An API can fall on either side depending on what it does and how the state defines the category.
The contract carries more weight here
Your customers have production systems that break when you do. Four terms do the work:
| Term | What it should say |
|---|---|
| Service levels | What uptime you commit to, measured how, with what remedy. A service credit is the normal remedy — cap it. |
| Limitation of liability | Capped at fees paid, with consequential loss excluded. Without this, a customer's lost revenue is theoretically yours. |
| Rate limits and fair use | Written down, so enforcing them is contractual rather than arbitrary. |
| Deprecation policy | How much notice before you break an endpoint. Your customers plan around this and will ask. |
Data protection sits alongside these. If customers send you personal data, you are processing it on their behalf, and their compliance obligations flow to you through a data processing agreement they will require.
Downstream dependency risk
Many API businesses are a layer over someone else's API. That is a legitimate business, but the upstream provider's pricing, availability and terms are your cost of goods and your uptime. Know what your terms commit you to when the layer beneath you fails, and make sure you have not promised more than you can deliver.
If you are not a US person
- No S-corp election — Section 1361 bars non-resident alien shareholders.
- Form 5472 with a pro-forma Form 1120 annually, $25,000 penalty for failure to file.
- Section 174A splits domestic and foreign development — current deduction for domestic research and experimental expenditure in tax years beginning after 2024, 15-year amortisation for foreign.
- Enterprise customers will ask where data is processed. Have an answer before the security questionnaire arrives.
When to revisit
| Trigger | What to reconsider |
|---|---|
| First enterprise customer | A real contract, a DPA, and a service level you can actually meet. |
| Unpaid usage becoming material | Prepaid credits or hard caps. |
| Crossing $100,000 into a state that taxes services | A determination on how your product is characterised. |
| Raising institutional money | Delaware C-corp. |
| Your upstream provider changing terms | Your own margin, and what you have promised customers. |
Dependable infrastructure needs a dependable company
Founders 8 holds the entity, the filings and the deadlines so nothing lapses while you are keeping uptime.
Build your workspaceFounders 8 does not provide tax advice. Tax residency depends on facts and rules specific to each jurisdiction — review your position with a qualified adviser.