In the first scenario, if you intend to earn less than € 12,500 in a calendar year, the best option will be to stay as ENI or Independent Worker.
The values are low and do not compensate for the work of creating and managing a company or the cost of accounting. Just start your activity on the AT Portal and since you are exempt from invoicing VAT, you do not need to submit the quarterly VAT declarations. And during the first year of activity, you are exempt from the payment of Social Security. It is also a good idea not to forget.
If, on the contrary, you plan to bill above that amount, it may already make sense to open a company. Mainly because it allows you to choose the salary amount you will receive as a manager of your own company. Of the total invoices you can leave part of that capital in the company as a form of profits to be able to use and invest in your business.
In the case of ENI, all amounts billed 75% are taxed under the IRS.
In the company, you have the freedom to do this management and thus reduce the paid IRS. The greater the amount you invoice in a calendar year, the more sense it makes to open a business as you will be able to plan the tax impact.
No less relevant is the question of whether you already have other sources of income.
First, because if the total of your income, not only as ENI, which is the category B income of the IRS, but also others, such as category A income, fall below the gross annual € 9,226, you are exempt from paying IRS. So, if you have no other income and you expect to bill less than € 12,500, it also makes sense to stay as ENI because in addition to the Social Security exemption during the 1st year, you do not pay IRS or VAT invoices.
If, on the other hand, you already have other sources of income, specifically category A (salaries for work for others), opening a company may be a good solution, regardless of the estimated volume of invoicing. This is because, if you can give up a salary in your company, you can waive the remuneration as a manager and you are exempt from paying Social Security for your company because you are already making Social Security discounts through the employment contract.
This scenario allows the amounts that you bill in your company to stay in the company to be able to use, for example, to pay some expenses related to your activity, and at the end of the year you can receive the profits in the form of dividends by paying a maximum tax of 28% (if you choose not to be included in the IRS). With the company you have more instruments to make tax planning more effective.