If each spouse has self-only HDHP coverage (neither spouse has family coverage), how much can we contribute?

With self-only high-deductible health plan (HDHP) coverage, each spouse can contribute up to the yearly maximum contribution for individual coverage.
If either spouse carries family HDHP coverage, both spouses are treated as having family coverage. The HSA maximum for family coverage will need to be split between both spouses upon agreement. This agreement could be that the spouse with family HSA coverage contributes the maximum while the other spouse waives his/her HSA for the year. The combination of contributions to the two HSA accounts cannot exceed the yearly maximum contribution for family coverage.