The maximum annual contribution limits are determined by the IRS each year and include both employer and employee contributions.
For 2018, the maximum annual contribution limit that an individual with single coverage can make to an HSA is $3,450. In the case of an individual with family coverage, the maximum annual contribution remains at $6,900. The minimum deductibles for 2018 are $1,350 for single coverage and $2,700 for family coverage.
Note that the contribution is not limited to the annual deductible under the High Deductible Health Plan (HDHP). The IRS allows for an additional contribution for those who turn 55 before the end of the tax year. The additional contribution amount is $1,000. If you had HDHP coverage for the full year, you can make the full catch-up contribution regardless of when your 55th birthday falls during the year.