I'm doing my father in law's taxes who passed away in Feb and I do not know if he received a lump sum from Social Security before. HELP
You can see the indication for lump sum on the form SSA-1099.
On this form in box 3, you would see something like (for tax year 2016):
"2015 benefits $5,000.00"
Of course, the year and the amount will vary.
Also note that you can have multiple years listed here, if the SSA paid money in 2016 for multiple previous years.
Note that the prior year benefits are included in box 5.
The point of the lump sum election is for TurboTax to choose which if two ways of computing the tax would be best for the taxpayer.
Also, the letters "LSE" (Lump Sum Election) often appear on line 20 of the 1040 in the open space to the left of 20b.