What invoice should I issue for writing a project for a public institution?

Just issue an ordinary invoice to the organization. If the institution doesn't need an invoice, just issue a receipt.

note:

Generally speaking, administrative institutions have administrative fees approved by the financial price departments at or above the provincial level, and they can use administrative fees fund bills (equivalent to the invoices of enterprises), and the money collected is generally turned over to the finance (two lines of revenue and expenditure); Receipts are used for non-settlement fund transactions within or between units; Some institutions should use invoices to carry out business of a business nature. Administrative units can only issue receipts and financial supervision receipts, such as driver's license fees. Because the administrative unit has no operating income. Tax stamps are also special receipts.

Institutions can issue receipts and invoices.

According to Article 8 of the Notice of the Ministry of Finance on Printing and Distributing (Caizong [20 10] 1No.), the following acts shall not be settled by funds: administrative institutions shall provide the following services on the principle of voluntary compensation, and their fees shall be business service fees, and tax invoices shall be used according to law, and they shall not be settled by funds:

1. Information consultation, technical consultation, technical development, transfer of technical achievements and technical service fees.

2. The expenses for the relevant units and individuals to voluntarily participate in training and meetings other than the mandatory training business as stipulated by laws, regulations and the State Council departmental rules.

3. International exchange service fees charged for organizing short-term overseas training and providing domestic services for foreigners working in China.

4. Service fees such as booth fees charged for organizing exhibitions and fairs.

5. Fees charged to subscription units and individuals for starting publications and publishing books.

6. Fees charged for carrying out activities and providing audio and video recording services.

7. Copying fee, typing fee and information fee.

8. Other commercial service charges.