People can own many companies and it has no bearing on if they have a full time job with someone else. In your case you would setup a 'Limitada' (Ltd) company and this can be done online at https://www.portaldaempresa.pt
I'm from the UK, setting up a company is easy, cheap. Each year I need to submit a small set of accounts, and a tax return. The first time you do this might seem hard, but it's basically form filling, and after the 2nd time it's much easier and simple.
Concentrate on your product, when you take on investment or make profit, look into setting up a company.
I believe it's common for a developer to have their own company to use to sell all their products over their carears.
I'd love to see that in my native Belgium!
The VAT I pay each quarter is just a sum of the VAT I typed in on entry. So generating and submitting the VAT return is literally just one click.
End of year tax is just the difference been costs and sales (profit). In the UK, HMRC, provide you this PDF form where you input the total sales etc, they calculate the tax for you. So it really is just form filling.
I believe being a native Belgium there is nothing stoping you from forming a UK company, nor taking it's profits back to Belgium?
However, if you want your income from the business to be counted as your income for purposes of a loan or mortgage, you'll have a much easier time if an accountant can certify that the business really exists! And for a small business you can get the accounts done for £200-300 a year, so I doubt many people do their own :)
when my Father set up his consultancy the main concern of HMRC was that he could do the complex task of calculating VAT (sales tax) correctly.
BTW I am being ironic it is not that hard to calculate 17.5%
You can start a sole trader business easily (and cheaply).
In many EU countries there is a scheme where students or full time employees can start side businesses as sole traders and not be liable for VAT and social security taxes. I am not sure if this exists in Portugal but you can check with your local bureaucrats.
Activity like this will increase your employability in most companies. It can be an issue in government regulated businesses such as insurance but they are used to telling employees to shut it down.. it's a non-issue for hiring.
You may own your employer but you are still an employee.
In Germany I would advise on an uGmbH, in US on a LLC and in UK on a LIC. Those are easy to fund, e.g. a Tennessee LLC cost only $100 annual franchise tax. Other states charge no franchise tax.
And you can't just pay yourself a salary which varies every month, you can change it once a year. You can pay yourself a variable bonus, but it can be a maximum of 35% of the salary. So paying yourself $1 salary a year and the rest as a bonus doesn't work.
UG is quite good if you have a stable business, but for everything else it seems a bit complicated.
At this point you are a registered freelancer and can run one person business, no employees, but you could have subcontractors. There is also no company, no .Inc.
You can go one step farther and register a company where you do establish legal entity with the .Inc attached to it. For simplicity you get the number/name and you can associate other branding name or names to make it marketing sexy. It's also rather simple, takes another hour and costs about $250 for starters, although I believe there are some variations where incorporation costs a bit more, but still a few hundred dollars.
Once you are incorporated the accounting becomes slightly more complicated. While being a registered freelancer you can pretty much do your own number adding for taxes, having the company means us are better of hiring part-time accountant to deal with the paperwork.
A lot of people in the technology/design/multimedia fields work as registered freelancers because there is no limit to income related to it, paperwork is simple and in Canada there is not culture of businesses suing each other all the time like in the US. So, there is no need to have separate legal entity to protect yourself. It's very convenient and many small businesses in the first year or two of existence run as a freelancer who hires other freelancers. Only once the business truly starts becoming a company and wants to provide perks and benefits to employees and also start looking 'bigger' on the market it is being registered as proper corporation.
I think it's a very valuable system for stimulating small business growth. The cost to try is very low and simple to do.
Also with regards to your chances of getting a full-time job. That depends. Most companies won't have a problem with that, but some might. They might not look kindly on the time commitment they think you'll have to put on your own company. A company that's operating in the same field as your company obviously would not most likely not hire you, because of your competing interest.
Always read your contracts and look for clauses regarding this. Most companies require you to disclose the fact that you work for another company / are doing contract work outside of your normal work time. Some companies forbid this (unless you ask them to change the contract, and if you explain the situation, many companies will oblige).
just my 2 cents, ignore if your market is something else.
Corporations are all about liability and ownership. As a student, you likely don't have any assets to protect. Once you take investment or add a partner, you'll need to do somethingn!
You should inform yourself.
In the US, Nolo is a good place to start. So is BusinessUSA. After that, you should find out the laws regarding running a business in your state, running a business in your county/parish, and running a business in your city/locality. Depending on your business structure, all four may have different requirements, forms, licenses, fees, filing dates, taxes (fed, state, county, city), etc.
It's not an insurmountable amount of work to handle on your own, especially if you choose a simple structure like a sole proprietorship or LLC, but you should do your homework before you jump in and contact a professional with any concerns you have.
Also, you should talk to a lawyer if you are worried about liability. The suggestion from some commenters that you are separated from liability if you run an LLC or other partnership is inaccurate. Liability is limited, but you can still be sued personally for fraud, negligence, and a host of other sins.