As I stated before CSA1099R """"""has a value in box 2a""""". Do I still need to calculate nontaxable portion using general or simplified method depending on dates?
The payer would be using the general rule when calculating the taxable amount. If they have entered a taxable amount for you, then they have already calculated the tax free amount for you. You can you can use the box 2a taxable amount and move forward. You would use the Simplified Method to calculate the taxable (and tax free) amount if box 2a were blank.