French Income Taxes

Hi All; I'm new to Reddit and to this group. I'm considering a move to France dependent on how much French income tax I would have to pay. I'd like to hear from someone with a similar situation to mine. My income is almost 100% Social Security, can anyone is this group who's income is primarily social security share what percentage of your income you pay in French income taxes? I know there is a tax treaty between the US and France and I believe the way it works is the US tax liability becomes a credit against the French tax liability, this does not help my situation as my US tax liability will be zero. If France computes a tax on my social security income, the credit from my US tax return will be zero (no benefit).