With the federal taxes, pension totals and taxable totals are different. Why?

[VolvoGirl]

Could be lots of reasons.  Is the amount on 1099R box 1 and 2a different?  The taxable amount can be different by the amount in box 5.  Like if you made an after tax contributions to the pension.  That's what I did, when I retired I was able to buy back more time.   So the plan keeps track of it and prorates it on the 1099R.  You would have to ask the plan why the taxable amount is different.   

[JulieS]

Yes, it's very common for the gross pension, box 1 Form 1099-R, to be more than the taxable amount in box 2a. 

Some common reasons this occurs:

• A portion of the benefit is used to pay for health insurance premiums. If this is the case, you will see the nontaxable amount in box 5. 
• Box 5 may also contain post-tax contributions or Roth contributions, which aren't taxable when they come out of the account. 
• You may have a roll-over, or conversion of part or all of a distribution, which is nontaxable. 
• If the distribution is a nonqualified annuity, only the earnings are taxed, not the original amount contributed to the annuity.