Question from 1040 “where is your distribution from” and thinking I should select General Rule since getting pension from my employer before retiring?
Since you're getting a pension from your employer, you'll likely want to use the Simplified Method for reporting it on your Form 1040. This method is easier and uses a worksheet to figure out the tax-free part of your payments. You can find more details and a worksheet in Topic No. 411.
However, if your plan is nonqualified, you should use the General Rule, which calculates the tax-free part based on your investment in the contract and the total expected return. For more info, check out Publication 939.