You must register your trade with the city or municipal administration (city hall) in which the business or business premises are opened (§ 138 AO - notifications of gainful employment).
You can also obtain the necessary registration forms there. Many municipalities already offer electronic procedures for this purpose.
In addition, you must notify your competent tax office of the opening of the business within one month (§ 138 paragraph 1b in conjunction with paragraph 4 AO). To do this, please complete the electronic questionnaire for tax registration for sole proprietorships. The electronic input help will assist you in completing the questionnaire. The prerequisite is the one-time creation of a ELSTER user account. Alternatively, you can create a ELSTER-Light account. With this account you can easily register for the announcement of the start of a commercial activity and later you have the possibility to convert the certificate into a regular certificate. This will then allow you to take advantage of all the benefits of ELSTER. The tax office will then assign you a tax number. Please use this tax number to file your tax returns, advance VAT returns and, if applicable, wage tax returns.
If the activity you wish to pursue is not commercial but freelance, e.g. as an architect, and no business registration is required with your city or municipal administration, you must independently notify your tax office of the commencement of freelance activity using the electronic questionnaire for tax registration for sole proprietorships.
If you are setting up a partnership, joint venture or corporation, you must complete the questionnaire for tax registration: Setting up a corporation or cooperative, corporation under foreign law, setting up a partnership or joint venture, or participation in a partnership or joint venture.