How OpenAI and Anthropic API billing works

Do OpenAI and Anthropic charge before or after API usage?

Mostly before. Both default to prepaid credits, and both invoice some contracted customers monthly.

New OpenAI API accounts use prepaid billing, per OpenAI’s prepaid billing article. Its invoice dates article says accounts can use prepaid credits or automatic card payments, and that Enterprise API customers receive invoices. Automatic card payments are collected at usage thresholds or monthly, depending on payment method and country.

At Anthropic, most organizations pay with prepaid usage credits, per its billing article. Organizations with an invoicing arrangement through Anthropic’s Sales team are billed monthly in arrears.

How do prepaid API credits work?

You buy credits first, and usage draws the balance down. The rules differ in the details.

OpenAI’s minimum purchase is $5 and the default is $10, per its prepaid billing article. Purchased credits expire after 1 year and are non-refundable except in the cases the article lists. Free credits get used before purchased credits. A trust tier, based on usage and payment history, sets the maximum balance you can hold. Access may not stop the moment credits run out, and usage in that gap shows as a negative balance that comes out of your next purchase.

At Anthropic, credits are bought on the Console Billing page by someone with an Admin or Billing role, and they’re available right away, per its billing article. They pay for API access, playground usage and Claude Code. They expire one year from purchase, and all credit purchases are non-refundable. Only successful API calls are billed, although a request that was on track to succeed is still charged if the client disconnects or times out. When credits run out, API calls stop until more are added.

That last rule is the one to plan around. An empty Anthropic balance stops your calls, while OpenAI may not cut you off the moment yours runs out.

How does auto-recharge work?

Both providers can buy credits for you when the balance falls below a threshold you set.

OpenAI turns auto-reload on by default during setup. You set the threshold, the balance to restore and an optional monthly reload limit, and the minimum recharge is $5. OpenAI notes that a recharge limit controls automatic purchases, not API usage.

Anthropic asks for the balance that triggers a purchase and the balance to reload to. If you’re already at or below the threshold when you turn it on, Anthropic charges right away, plus applicable taxes.

What are usage tiers?

Usage tiers set how much an organization can use each month and how fast it can send requests. Both providers move organizations up automatically.

Detail	OpenAI	Anthropic
Tier names	Free, Build, Launch, Grow	Evaluation, Start, Build, Scale, Custom
How you move up	Total credit purchases reach $5, $100 and $500	Usage history and account standing
Monthly ceiling by tier	Usage limits of $100, $500, $5,000 and $200,000	Spend caps of $500, $1,000 and $200,000 for Start, Build and Scale
Rate limits	Per organization and project, varying by model	Per organization, by tier and model class

OpenAI figures come from its rate limits guide. Anthropic figures come from its rate limits page, which says Custom tier organizations have no monthly spend cap and new organizations may start in an Evaluation tier with lower limits.

Hitting Anthropic’s tier cap pauses API usage until 00:00 UTC on the first day of the next month, unless the organization gets a higher limit sooner.

How do spend limits work?

Spend limits are caps you set yourself, below the provider’s own ceiling.

OpenAI has two kinds, described in its usage and spend limits article. A spend alert sends a notification and lets traffic continue. A hard spend limit stops affected requests. You can set either one for the organization or for a project. A hard limit resets with the next monthly cycle, and because enforcement isn’t instantaneous, recorded spend can slightly exceed it.

Anthropic lets you set a spend limit below your tier’s cap on the Console Billing page, per the rate limits page. Once usage reaches it, requests return an HTTP 400 error until access resumes or the limit changes. Workspaces can have their own limits too.

Where do you find invoices and receipts?

Both providers keep billing documents in their consoles.

At OpenAI, individual and team customers see payment history and available invoices or receipts in Billing history. Enterprise API invoices cover calendar-month usage, download from the Billing section, and are typically issued within 2 weeks after the cycle ends. That’s from OpenAI’s invoice dates article, though another OpenAI article says usually a few days.

Anthropic gives prepaid organizations a receipt for each credit purchase, auto-reload purchases included. Organizations on a usage contract get a Stripe invoice at the end of each calendar month. Each invoice is emailed with the subject “Your receipt from Anthropic” and listed under Invoice history on the Billing page, per Anthropic’s invoices article. Invoices below $0.50 roll into the next invoice.

How are taxes handled?

Tax details come from the billing information on file when an invoice is issued. Get them right before the invoice goes out, because neither provider applies a change to an invoice it has already issued.

At OpenAI, billing admins add a Tax ID in the organization’s billing preferences, and changes apply only to future invoices. An invalid Tax ID may be removed, and applicable taxes may then be charged, per OpenAI’s Tax ID article.

At Anthropic, the name, address and tax information on an invoice come from the billing details at the time it was issued. Issued invoices can’t be changed, per the invoices article.

What counts as a paid charge?

Money the company actually paid the provider. That means a credit purchase, an automatic card payment or a paid invoice. Credits the company didn’t buy are a different thing. Both providers spend their free or included credits before purchased ones.

OpenAI uses free credits before purchased credits, per its prepaid billing article. Claude Max and Team plans include monthly API credits, which Anthropic spends before purchased credits. Unused ones expire each billing cycle, per its billing article.

On an Anthropic invoice, a negative “Applied balance” line is existing credit being used. It isn’t a new charge or a discount, per the invoices article.

How do OpenAI and Anthropic billing compare?

Detail	OpenAI	Anthropic
Default payment	Prepaid credits for new accounts	Prepaid credits for most organizations
Other payment options	Automatic card payments, Enterprise invoices	Monthly invoicing through Sales
Minimum credit purchase	$5	Not stated in the cited article
Credit expiry	1 year	1 year from purchase
Refunds	Non-refundable, with listed exceptions	Non-refundable
Auto-recharge	On by default at setup, optional monthly limit	Threshold and reload target
Tiers	Free, Build, Launch, Grow	Evaluation, Start, Build, Scale, Custom
Your own caps	Spend alerts and hard limits, per organization or project	Spend limit below tier cap, per organization or workspace
Where receipts live	Billing history	Email and Console Invoice history
Credits you didn’t buy	Free credits, used first	Max and Team monthly API credits, used first

Per-token rates are on OpenAI API pricing and Anthropic API pricing. To keep both providers’ charges in one place, read how to track AI API spend.

For a closer look at Claude invoices, there’s Anthropic API billing explained on the ernd blog. To estimate a monthly bill at list prices, try the AI API cost calculator.