Green card filing for parents - Income Tax Returns requirements

[MayurN]

I am a US citizen.  I finished my undergrad last year and started working in US.  I want to file for green card for my parents as soon as possible.  My current income and my assets are well above the stipulated baselines.  However, I read in some websites that I need to have 3 years of income tax returns while applying for green card for my parents.  

I would like to know

1. If I really need IT returns for 3 years, or 2 years' returns are sufficient?

2. If I need 3 years' IT returns, do all 3 returns need to show income above stipulated baseline income?

Please advise.

Thanks in advance

[newacct]

Current income is what's important. You don't necessarily need to have filed tax returns for any number of years, if you didn't have income in those years.