uncertain tax position is basically an accounting term and it  relates to the earnings recognition provision for  the issue.

for so many reasons the large & sophisticated taxpayers takes the aggressive positions on his  tax returns & report taxes due to  IRS that are significantly lesser  than  amount for  tax they will ultimately pay

Step 1: Recognition.

Under  the FIN 48,  FASB might not recognize  the benefit relate to the uncertain tax position in a  financial statements unless if it is  (more than 50 percent probable) MLTN position will be sustained based on solely  its technical merits.

Step 2: Measurement.

Tax benefit of  the qualifying position is measured like largest amount for tax benefit which is more than 50 % likely to realized upon the ultimate settlement with the taxing authority. This whole poses significant challenges for evaluating tax positions in the various state, foreign jurisdictions and local.