Gemini Invoices and Tax ID: API Key Setup, First Call

Google's official documentation states that purchasing services through Google Play in Taiwan will send a unified invoice; if the transaction counterparty is Google Asia Pacific and a Taiwan tax ID has been provided, no Taiwan GUI is issued. Check the actual payment documents for your purchase channel. Google verification date: 2026-09-24. Google Payments Taiwan GUI official guide.

Google Gemini API Key Setup and First Request

The Gemini API key is managed in Google AI Studio and bound to a Google Cloud project. After you create a key, you can use the official Gemini API, or connect through a compatible API format to the Gemini models in the model catalog. Keys newly created in AI Studio have defaulted to authorization keys since 2026-05-28. Google's official documentation indicates that standard keys will stop being accepted in September 2026, so existing projects should first check their key type and complete the migration.

Applying for a Gemini API Key in Google AI Studio

1. Sign in to Google AI Studio and open API Keys in the left-hand Dashboard.
2. New users can use the default project created by AI Studio. If an existing Google Cloud project does not appear, first import it under Projects → Import projects.
3. On the API Keys page, select a project and click Create API key. Confirm the Key Type; new keys default to auth keys.
4. Store the key in the GEMINI_API_KEY environment variable. Do not put the key in public web pages, front-end code, or code repositories.

Official AI Studio project and API key documentation, verified 2026-09-24: Using Gemini API keys, Gemini API quickstart.

First Request: Google Gemini API generateContent

This example uses the official REST endpoint and the x-goog-api-key header, with model ID gemini-3.8-flash.

export GEMINI_API_KEY="your Gemini API key"
curl "https://generativelanguage.googleapis.com/v1beta/models/gemini-3.8-flash:generateContent" \
  -H "x-goog-api-key: $GEMINI_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"contents":[{"parts":[{"text":"Explain the Gemini API in one sentence in Traditional Chinese."}]}]}'

Official GenerateContent REST documentation, verified 2026-09-24: API reference.

Calling Gemini in OpenAI-Compatible Format

If your application uses the OpenAI SDK or Chat Completions, you can set the base URL to https://api.bazaarlink.ai/v1 and call gemini-3.8-flash from the public catalog with a BazaarLink key.

export BAZAARLINK_API_KEY="your BazaarLink key"
curl https://api.bazaarlink.ai/v1/chat/completions \
  -H "Authorization: Bearer $BAZAARLINK_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"model":"gemini-3.8-flash","messages":[{"role":"user","content":"Explain the Gemini API in one sentence in Traditional Chinese."}]}'

Gemini API Pricing and Model Selection

Google's official standard paid prices (per million tokens) currently list Gemini 3.8 Flash at US$0.75 input / US$3.75 output (through 2026-12-31), and Gemini 3.1 Pro Preview at US$2 / US$12 when the prompt does not exceed 200,000 tokens. Free-tier availability varies by model. Gemini 3.8 Flash's official page also indicates a Free Tier, and the data-use terms for paid and free tiers differ. Check the AI Studio project for each model's usage limits and billing settings.

Pricing and free-tier verification date: 2026-09-24. Sources: Google official Gemini pricing, key management documentation, BazaarLink public model list and cache/discount catalog. For model details in the current catalog, see the Gemini 3.8 Flash model page and the Gemini 3.1 Pro Preview model page. For cost estimates, see the Gemini API pricing guide.

Once the API is connected, read the original Taiwan purchasing and invoicing sections below, and compare the OpenAI API, Claude API, and cross-model price list. Check the invoice type against your actual purchase channel and the transaction documents you receive.

Query date: 2026-09-01 (Taipei time). Policies change. Every judgment in this article is labeled with its source and query date. Before purchasing, follow what your account's checkout page actually shows.

Does a Gemini Subscription Issue a Taiwan Unified Invoice?

It depends on which channel you buy through. The same Gemini can produce completely different results depending on the channel.

The most common misunderstanding is the second row. Google's payment center does have a "Taiwan tax information" field where you can enter an 8-digit tax ID, but being able to enter it does not mean a unified invoice will be issued. Many companies only discover this when their accountant rejects the expense.

Why Is This? The Key Is "Who Holds a Taiwan Tax Registration"

In Taiwan, a unified invoice (GUI) can only be issued by business operators that have completed tax registration in Taiwan.

• Google Play has a collection and remittance mechanism with tax registration in Taiwan, so it can collect 5% business tax as required by law and issue unified invoices. Google's official page explains how to find the "Taiwan government unified invoice (GUI)."
• Official-website B2B services follow a different billing path. The tax ID you enter appears on the receipt, but that document is not a unified invoice.

So the rule is simple: don't check whether there is a tax ID field. Check whether the document you receive is a GUI.

This is not speculation. The Ministry of Finance publishes a public list, "Overseas e-commerce operators that have issued cloud invoices," which lists every overseas company that has completed cross-border e-commerce tax registration in Taiwan. As of the 2026-09-02 query, Google Asia Pacific Pte Ltd has been registered since 2017-05-01, with status "operating."

However, "being registered" covers the obligation to collect business tax from Taiwan individual consumers and issue cloud invoices. Its nature is a voucher for individuals' bookkeeping, which is a different thing from the triplicate unified invoice businesses use to deduct business tax. This explains why the same Google issues a GUI for Google Play (aimed at individual consumers) but not for Workspace direct purchases (aimed at businesses). It is not that Google isn't registered. The scope of the registration obligation simply does not cover this type of transaction.

How Do I Enter a Gemini Tax ID? How Do I Check What I Received?

Three steps:

1. Sign in to the Google Payments Center.
2. Go to "Settings" and find "Taiwan tax information." Check whether the account type is "Organization" (Business).
3. Download the receipts from transaction history, and check the file itself: is it a "unified invoice" (with an invoice number in the format of two English letters followed by 8 digits), or a "receipt / Receipt / monthly statement"?

If what you download is a monthly statement or an English receipt, it is not a unified invoice, and accounting cannot book it directly as an input-tax voucher.

Accounting Requires a Unified Invoice. What Are My Options?

Ranked by your actual needs:

① Individual or small amounts: switch to purchasing through Google Play. If you are buying a personal Google One AI plan, purchasing through Google Play usually gets you a unified invoice. This is the simplest route.

② Enterprise wants Workspace + Gemini: find a Taiwan reseller. Don't buy directly from the official website. Purchasing through a Taiwan Google reseller can yield a triplicate electronic invoice, which also fits most companies' procurement and expense-claim processes.

③ You only need to call Gemini models: use the API, not a subscription. This is a route many people overlook. If your need is "calling Gemini in a program" rather than "using the Gemini web version," then what you need is the API, not a subscription. And the API can be purchased through Taiwan platforms, which directly yield a unified invoice.

⚠️ But first confirm that your need really is the API. If you need the web interface, Google Docs integration, or features inside Workspace, the API cannot replace any of those.

For Research Grants or Public-Sector Funds, Check the Reimbursement Deadline First

A constraint that is often overlooked in practice: when funds have a reimbursement deadline, a monthly-billed subscription is often not feasible. Once the deadline passes there is no budget source, and a subscription keeps charging continuously.

In such cases you usually can only choose a one-time purchase (for example, an API with a fully pre-purchased quota). Confirm the reimbursement method with your accountant before purchasing. That matters more than comparing prices.

Official Purchasing Routes for the Gemini API

If you decide to go with the API, Google offers two official routes:

Google AI Studio: tied to a Google account plus a credit card, priced in US dollars. The free quota suits trying things out. For production usage you must link a card, and billing is in foreign USD.

GCP Vertex AI: billed through Google Cloud. If your company already has a GCP contract and a Taiwan reseller, you can use the existing invoicing process. But you must handle Vertex's API format and IAM permissions, which sets a higher bar for teams that only want to call one API.

⚠️ The two have different API interfaces. If you later want to mix in GPT or Claude, you will have to integrate each one separately.

What About Taiwan Local Platforms?

If what you need is pricing in New Taiwan dollars, unified invoices, and no need to integrate a different API for each model, a Taiwan-based aggregation platform is one route.

BazaarLink is an AI API platform operated by 集聯科技有限公司 (Tax ID 62232477), a Taiwan company:

• Gemini models and GPT, Claude, DeepSeek, and others share a single OpenAI-compatible API. Switch the base_url to use it.
• Priced in New Taiwan dollars, issuing electronic unified invoices (two-part or triplicate, both available), and enterprises can negotiate monthly billing.
• New Taiwan dollar unit prices update daily with the exchange rate and can be checked on the model list.

from openai import OpenAI
client = OpenAI(
    base_url="https://bazaarlink.ai/api/v1",
    api_key="sk-bl-YOUR_KEY",
)
r = client.chat.completions.create(
    model="google/gemini-2.5-flash",
    messages=[{"role": "user", "content": "Hello"}],
)

But be clear about when it is not a good fit:

• You need the Gemini web version, Google Docs or Sheets integration, or the AI features inside Workspace. The API cannot replace these, so go through the official channel or a reseller.
• You already use GCP heavily and have a reseller contract. Routing through Vertex AI and consolidating into existing billing is more efficient.
• You only do small personal trials. The AI Studio free quota is enough, and no separate purchase is needed.

Sources and Query Log

• Google Payments Center: Where can I find my Taiwan government unified invoice (GUI)? (queried 2026-09-01)
• Google Payments Center: Taiwan tax information (tax ID entry field; queried 2026-09-01)
• Google Workspace admin help: Update tax information (queried 2026-09-01)
• Google Cloud: Get billing documents (invoices, monthly statements, receipts) (queried 2026-09-01)
• Ministry of Finance e-Invoice Integrated Service Platform: Overseas e-commerce operators that have issued cloud invoices (cross-border e-commerce tax registration list; queried 2026-09-02)
• Further reading: How to expense AI API costs at a Taiwan company? 2026 complete guide

TWD billing · Taiwan invoices · leading AI models · OpenAI-compatible API