There is at least on insurance company which issues Forms 1099-R with the taxable amount greater than the distribution amount under these circumstances, which I believe is improper. It makes no sense to tax something that is not being considered as having been distributed to you. I suspect that the taxable amount is correct but the insurance company is underreporting the amount that should be present in box 1. Others posting here who have had this problem under these circumstances do not seem to have not gotten the insurance company to make any changes to the amounts on the form.
A loan offset distribution taxes on the outstanding balance of a loan, cash that was previously paid to you but not previously reported as a distribution. The amount of the offset should be included in box 1, and I suspect that the insurance company is failing to include this. The loan represents an asset of the plan, so you can think of the offset distribution as being a cash distribution of the value of that asset which you then simultaneously pay back to the plan to satisfy the outstanding loan.
