The screen on which you enter "personal" HSA contributions is "Let's enter your HSA contributions" (see screenshot below). The first line is indeed not editable, because it comes from your W-2 in box 12 with a code of W. To edit the first line, you must return to the W-2.
Note that the W-2 amount is the sum of your employer's contributions and your contributions by means of payroll deduction - together called "the employer contribution".
The second line (your "personal" contributions) are contributions that you sent directly to the HSA, not through your employer.
Note that some taxpayers accidentally make entries that lead TurboTax to think that there is an excess contribution when there is not. Please read the following to see if any of these common situations apply to you:
One of the purposes of the HSA interview is to determine your annual HSA contribution limit.
As you probably know, the maximum limits in 2017 are:
However, these limits assume that you were in an HSA all year. If you left the HSA during the year or started Medicare or had one of a number of change events, then the limit is reduced.
There are several major culprits for excess contributions (other than just actually contributing more than the limit).
First, if you did not complete the HSA interview - that is, go all the way until you are returned to the "Your Tax Breaks" page - the limit still might be set to zero, causes a misleading excess contribution message.
There are questions all the way to the end of the interview that affect the annual contribution limit.
Second, it is not unusual for taxpayers to accidentally duplicate their contributions by mistakenly entering what they perceive to be "their" contributions into the second line on the "Let's enter your HSA contributions" screen (see screenshot below).
Normally, any employee who made contributions to his/her HSA through a payroll deduction plan has the contributions included in the amount with code "W" in box 12 on the W-2. This is on the first line on this screen (above). Don't enter the code W amount anywhere on the return other than on the W-2 page.
Third, if you weren't in HDHP coverage all 12 months, then the annual contribution limit is reduced on a per month ratio. NOTE, this means that you have to indicate when and under what type of HDHP plan you had. Be sure to answer the questions on the screen entitled "Was [name] covered by a High Deductible Health Plan in 2017?" (see screenshot below).
Fourth , if you had a carryover of excess contributions from 2016, then this carryover is applied to 2017 as a personal contribution, which could cause an excess condition in 2017 as well. But note: if you had an excess contribution in 2016 but cured it by withdrawing the excess in early 2017, then do NOT report an "overfunding" on your 2017 return.
Fifth, the Family limit
($6,750) is for the aggregate of contributions by both taxpayers, even if both
taxpayers have their own HSAs. That is, one taxpayer can’t contribute $6,750 to
his/her HSA and the other contribute $3,400 to the other HSA – the $6,750 limit
applies to the aggregate of all HSA contributions credited to the family (in
this case, the excess contributions would be $3,400).