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.
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.
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)
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.
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.