I'm prevented from changing Line 26d to $3,000 instead of $6,000. As a retired public safety officer I had this problem from last year when it did the same error.

[dmertz]

You must make the change on the Form 1099-R entry.  You are permitted to enter a maximum of $3,000 for PSO health insurance only for the one Form 1099-R from the PSO employer who sent the payment to the insurance company.  Do not enter it on any other Forms 1099-R.

[rodmoxley]

I had the same problem.  The way I got around it was to use the EDIT drop-down menu & selecte OVERRIDE to type in $3,000, rather than the incorrect $6000.  I hope that was an okay way to do it....at least I no longer get an error code!  TurboTax should re-design this section.  I go through this problem every year.