TL;DR: You declare the income from your micro-enterprise using tax return no. 2042-C-PRO, in addition to tax return no. 2042. The available sources do not make it possible to indicate the exact box number: it depends on the income category and the applicable regime.
Which form to use
You must use tax return no. 2042-C-PRO, identified as CERFA no. 11222, in addition to the comprehensive tax return no. 2042. It is used to declare income from a non-salaried activity.
Why the box number cannot be specified
The available information confirms the forms and the principle of filing, but it does not provide the correspondence between each activity, the income category, the applicable regime and the box number.
You therefore cannot reliably determine a specific box based solely on the information provided.
Income category to take into account
The box depends in particular on the category under which your income is taxed. The sources distinguish between industrial and commercial profits and non-commercial profits, but they do not provide the table linking each situation to a specific box on tax return no. 2042-C-PRO.
Information not available in the sources
The sources provided also do not specify a particular deadline for this micro-enterprise income tax return. They do not detail any documents that may need to be attached in each situation.
Informational content, not personalized tax advice.