Because the calculator does not really take into account the 35% social security if the money is paid by a foreign entity to the foreigner directly.
@binarycrusader: I can‘t reply below. It‘s not 35% but 34,75%. It‘s easy to find that online and this rate is not depending on the person. A foreigner or nomad does by definition not have a Portuguese employer. They have to pay the employer part themselves. It‘s that simple.
@binarycrusader: It‘s mentioned on countless sites related to the NHR and Golden Visa and all of these things. I talked this through with two Portuguese accountants. Is that enough?