My wife and I went to Brazil and our baby was born there, He received a Brazilian passport and his mother an I received ID card called RNE and it is valid till 2026.
We have stayed in Brazil for about six months and I really liked the country and the people of Brazil a wonderful country, Visited Brasilia, Sao Paulo and Rio during my stay.
After the baby was born we stayed for 2 months and I went back to my country. I am planing to come back to Brazil and settle there after I finish my work and save a good amount of money so I can open a business over there, since I saw there is a great business potential. I am not sure how many years I need to stay outside of Brazil to be ready. I am learning Portuguese now with my wife so we when we come back we do not struggle while ordering pizza again 
My question is, Since my RNE says it is valid for 10 years, how much time I can stay out of the country without losing the RNE ? Is there a period of time that I need to maintain for the RNE to be valid ? If I came back what do I need to do so they can know I came back ? in bottom line I want to keep my residency in Brazil and maintain it what do i need to do.
A brazilain son - VISA
In order to keep the RNE valid you must enter Brazil once within every 2 year period.
Also after completing 1 year you and your wife are eligible to start your naturalization process.
Yes, I very recently left and re-entered Brazil and upon leaving, the authorities confirmed that I had two years to return in order to not invalidate the RNE.
The two years is correct. Also your other question about how do they know? They know by the stamp in your passport.
Jim
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