Ask your employer why you have a code P in box 12 of your W-2, and what the code is supposed to be. You might be misreading it, or they might need to issue a corrected W-2, depending on what the correct code is. Could it be a poorly printed B or R or some other letter?
There is room for 4 entries in box 12 of the W-2. They are usually labeled 12a, 12b, 12c, and 12d. Each entry has a one-letter or two-letter code and an amount. The a/b/c/d is not the code. There is no box 12 P.