Expat taxes

I have heard that the tax law is going to be changing in March for expats.   

I have a possible accountant to check out our specifics but would not mind other recommendations.

Also I believe there must be some set regulations on what is taxed and at what rate. . We will have US social security and a couple of other retirement accounts.  We also have  an investment account with  stocks and bonds.

Not huge but enough to give us monthly income that along with others keeps us in good shape where we can also afford some travel. 

Does anyone have information on how the per percentages  are  figured out?    Before paying an accountant for specifics  I want to find out if realistic for us.   If we would have enough to

live comfortably. 

if anyone has mot info it would be greatly appreciated. 

I do have German citizenship, have never worked or earned money there. My husband will be with me.  We are visiting Portugal in May and are setting up a appointment with the attorney.

thanks for any advice.