Depends on the nature of the distribution (type of plan) and box 7 code.
TurboTax will ask follow up questions to determine the taxable amount.
Pension?, 401(k)? other?
I would consider it other? It is a program that the govt. funds pensions after a company declares bankruptcy and shift the pension liabilities to the taxpayers. I don't know if it's considered regular pension or not .
A turbotax help line employee advised me to put in a zero in the box 2a if it is blank, but the Turbotax instructions specifically say not to do that and not to put a number in that box unless you know what it's supposed to be. Putting a zero in that box means that I'm telling the IRS that the authors of that box in fact told me that the amount is not taxable and that is not the case.
No, Do not put zero. That will make it not taxable. Box 2b (not determined) is probably checked. Then plan administrator should have been able to determine the taxable amount, but unless you have a basis in the account and use the simplified method, probably it will all be taxable.
Unless this is the first year you have received the pension, you should use the same method that was used last year.