Do you run a business (trade) in Germany and generate a trade income of more than EUR 24,500 per year?
Then you are obliged to submit a trade tax return to your tax office. In it, you declare how high your trade income was in the past calendar year (assessment period). You submit a trade tax return for each assessment period in which you operated your business (annually). You must submit the declaration electronically, for example via www.Elster.de. In doing so, you declare further additions or deductions based on your profit or loss (simplified: income minus expenses).
You also state the municipality in which you operate your business.

The tax office determines the trade tax assessment amount and issues an assessment notice.
The tax office determines the trade tax assessment amount by multiplying the trade income by the tax assessment rate of 3.5 percent. This measurement amount is the basis for the amount of trade tax.

The tax office informs the municipality in which you operate your business about the trade tax assessment amount.

The municipality will send you a notice of the trade tax you have to pay or which the municipality will reimburse to you.
The municipality calculates the trade tax from the trade tax assessment amount of the tax office multiplied by the trade tax assessment rate of the municipality. Each municipality determines its own assessment rate.

With the trade tax assessment notice, the municipality also decides on the advance payments of trade tax to be paid by you in future for the following assessment period.

You pay the amounts specified in the trade tax assessment and/or advance payments for trade tax to the municipality on the date specified therein.