The reason for the change that you saw on your return when you entered that you had a HDHP is due to the HSA contribution that is included on your W-2 and the order that the information is entered into TurboTax.
Entering information into your return regarding HSA contributions
is a two-step process. Each step is likely to cause the
refund/balance due number to change because TurboTax constantly updates the calculations as you go through the return.
The first step occurs when you enter your W-2 that includes contributions to the HSA. After entering the information from your W-2,
the amounts contributed to the HSA are included in your income as an excess contribution (thus causing a
higher balance due or lower refund).
Then, the second step is to verify
your eligibility to contribute to the HSA due to coverage under a High
Deductible Health Plan. This results
in the HSA contribution being removed from income since you were eligible to
make the contributions. Therefore the
balance due amount will drop or the refund amount will increase.
