After the 2017 Publication 969 was released, the 2018 inflation-adjusted amounts for HSAs were published in Revenue Procedure 2018-18, and subsequently in Revenue Procedure 2018-27. If you viewed or downloaded the publication, please note the following for the first “Tip” on page 5. Revenue Procedure 2018-18 (dated March 5, 2018) lowered the HSA contribution limit for individuals with family HDHP coverage to $6,850. Revenue Procedure 2018-27 (dated April 26, 2018) raised that limit back to $6,900. The limit stated in the publication is correct. For 2018, if you have family HDHP coverage, you can contribute up to $6,900. The contribution limit for self-only HDHP coverage remains at $3,450.

Source: https://www.irs.gov/forms-pubs/2018-hsa-contribution-limit-for-individuals-with-family-hdhp-coverage