Tax office document request: subletting

The tax office required the following documents and information - Calculation of income from subletting I submitted the tax return via CHECK24 and already provided the information about the subletting in euros. I paid 1050 euros rent (flat rate) to the landlord. I received 980 euros in rent (flat rate) from the subtenant. What else should I tell the tax office? This is the first time I have done my own tax return. Thank you in advance!