If you have a rollover code G, the amount that is rolled over is not taxed, but it must be reported to the IRS.
For instance, if you have a pension of $10,000 and roll over the entire amount, the $10,000 shows on Form 1040, Line 4a, but it is not included in the taxable amount on Line 4b. If it shows up on Line 4b, you should review your entries for Box 2a of your 1099-R. If it's a complete rollover, the taxable amount in Box 2a of the 1099-R should be zero.
If you take a "normal distribution" Box 7, code 7, the distribution is normally taxable and is reported on both Line 4a and 4b of your Form 1040.
