I am trying to figure out if we are eligble for a refund of the social security and medicare taxes if we leave US after 6 years of H1-B employment?
No refunds, but if your home country has a bilateral agreement with USA then you will get the retirement benefits when you retire in that country.
How much tax (%) is taken from ones monthly salary assuming one earns a monthly gross of $5000?
I undersatnd a US citizen (nurturalised) who decides to move back to his/her native country would still be required to pay tax to the US government; how far is this true?
Plus...you should have minimum 40 credits to get social security benefits. Every year you get 4 credits (1 per quarter). That means you should work in this country for atleast 10 years in order to eligible for social security benefits.
Hmm.. not exactly. You can earn 4 credits per year, but each credit is earned based on what you earn. For 2008 every 1050 earned gains you 1 credit point. So if you are in IT and on H1, you pretty much get all your credits within the first month or two of the year.