HSA contribution split

[jpsolver]

My spouse has a family HDHP self + children and I have a self-only HDHP. I understand that we should go with the family contribution limit of $8,300. My question is whether we can split the contribution as we wish, for example, my spouse contributes $8,000 and me $300, or equal amounts $4150 x2. 

[Mike9241]

under the rules if one spouse has family coverage both are treated as having family coverage.  therefore, how you split the maximum $8300 contribution for 2024 is a matter of personal choice.  A form 8889 must be filed for each spouse that has an HSA. so having one saves a little paperwork. also, up to an extra $1000 can be contributed to the account of a spouse who is 55 or older (at year-end) or up to an extra  $1000 to each account if both are 55 or over)

[Opus 17 · Accepted solution]

Although you are covered by a single HDHP, there is a provision in the regulations that if one spouse is covered by a family HDHP, both spouses are treated as if they are covered by a family HDHP for purposes of the contribution limit.  The ultimate family limit for 2024 is $8300, and you can divide it any way you want. 

[Opus 17]

As noted, the extra $1000 catch-up is personal and can't be split, it can only go into the account of the person who qualifies.

And there is one more factor I forgot to mention.  If one plan is payroll deductions and the other plan is direct contributions out of pocket, the payroll deduction will save a little extra on taxes.  Both reduce your income tax, but payroll contributions also reduce your social security and medicare tax withholding.