TurboTax calculates the maximum permissible contribution correctly, provided that you've answered all of TurboTax's questions related to this correctly. If you've entered everything correctly, it's likely that not all of the information needed to calculate the maximum permissible contribution was conveyed to the HSA custodian or the HSA rep was simply mistaken. Perhaps the HSA rep was referring to the overall maximum and not to other limitations such as those due to not being eligible all year, not taking your age into account correctly or not taking into account contributions that your spouse might have made.
