Here are a few options for a WordPress `post_tag` description for “開發票” (fā kāi piào – Issuing an Invoice) in Traditional Chinese, each with a slightly different focus:

**Option 1: General & Concise**

* **Description:** 關於開發票的相關資訊，包括發票格式、開立流程、稅務規定和常見問題。 (About the related information of issuing an invoice, including invoice formats, issuance process, tax regulations, and frequently asked questions.)

**Option 2: Focus on Practical Information**

* **Description:** 了解如何正確開發票，包括如何列印、如何填寫，以及常見的開發票錯誤。 實用資訊，助你輕鬆處理發票事宜。 (Learn how to issue invoices correctly, including how to print, how to fill them out, and common invoice errors. Practical information to help you handle invoice matters with ease.)

**Option 3: SEO-Focused (Keywords Included)**

* **Description:** 探索開發票的稅務知識、電子發票、發票系統及相關規定。 獲取開發票流程的指南，了解如何申報、管理發票，以及常見的開發票問題。 (Explore the tax knowledge of issuing invoices, electronic invoices, invoice systems, and related regulations. Obtain a guide to the invoice issuance process, learn how to declare and manage invoices, and address common invoice issues.)

**Option 4: Business-Oriented**

* **Description:** 針對企業和商家，提供開發票的專業建議。包括正確的發票開立方式、稅務考量、符合法規的實用指南，以及如何優化發票管理流程。 (For businesses and merchants, providing professional advice on issuing invoices. Including the correct method of issuing invoices, tax considerations, a practical guide in compliance with regulations, and how to optimize the invoice management process.)

**Considerations when choosing:**

* **Target Audience:** Who are you writing for? (e.g., general public, business owners, etc.)
* **Post Content:** What kind of content will be in the posts tagged with this tag? (e.g., tutorials, news, legal updates)
* **SEO:** Do you want to optimize for search engines? If so, choose an option that includes relevant keywords (like Option 3).
* **Length:** Keep the description concise, but informative. WordPress often truncates longer descriptions.

**How to Set the Description in WordPress:**

1. **Go to Posts -> Tags** (or Categories if the tag is a category) in your WordPress dashboard.
2. Find the tag “開發票” and click “Edit”.
3. In the “Description” field (usually a text box below the tag name and “slug”), paste your chosen description.
4. Click “Update”.

Choose the description that best suits your needs and content. Good luck!