President Obama’s re-election and the Democrats’ retained control of the Senate mean that a repeal of the Patient Protection and Affordable Care Act before its tax provisions go into effect in early 2013 is highly unlikely.

As a result, investors now fear a potential top tax rate as high as 43.4 percent due to the combined impact of expiring Bush tax cuts and a new ‘‘Medicare surtax’’ on investments. Anticipating the rate increase, tax advisers have been actively engaged in planning to avoid or minimize the new surtax.