Move from Family to Individual Coverage
You have family HDHP coverage. So you can can contribute a maximum of $7,000 to your HSA in 2019. But then in July, you have a mid-year status change. You switch to self-only coverage. Self-only coverage allows you to contribute a maximum of $3,500 to your HSA in 2019.
From January to June (6 months), you were eligible to contribute towards the family limit. As such, you would take 6/12, with 12 being the total number of months in the year, and multiply it by the family annual limit of $7,000. The result is $3,500. Then because from July – December you are covered under self-only coverage, you would multiply 6/12 by $3,500. The result is $1,750.
The result is a total contribution of $5,250 for the entire year.