I am an immigrant and I want to bring money from my country to the US. I know I have to declare the amount of money if it is more than $10,000, However I don't know the tax policy on my money. Do I have to pay tax on it and if yes, what is the percentage approximately?
Money and Other Monetary Instruments
You may bring into or take out of the country, including by mail, as much money as you wish. However, if it is more than $10,000, you will need to report it to CBP. Ask the CBP officer for the Currency Reporting Form (FinCen 105). The penalties for non-compliance can be severe.
"Money" means monetary instruments and includes U.S. or foreign coins currently in circulation, currency, travelers' checks in any form, money orders, and negotiable instruments or investment securities in bearer form.
Imports of cash or cash equivalent to the US are not taxed.
Green card holders are subject to US income tax on their worldwide income, however, so if you acquired any of that money while you were a US permanent resident, you will have reported it on the tax return for the appropriate year, and it will already have been taxed.