It does depend on your overall income. Basic idea is this:
*divide your SS benefits by two;
*add that 50% to your other income (including various "tax-exempt" income, such as interest on state & local government bonds)
If the total is higher than $25k for a single person ($32k for a married couple), then you go to the spreadsheet from hell to calculate how much of the benefits are taxable.
In general terms, for most people of moderate means it will be roughly 50% of the benefits taxable; for high income it can be as much as 85% of the benefits taxable.
Plus if your total income is above a certain threshold your Medicare premium doubles.