Individual income taxes in the US are usually cash basis (it is poasible to change to accrual, but from what I understand it almost never makes sense for an individual to do so.)

And only individual income taxes would be directly relevant to individual ACA subsidy eligibility.

Didn't receive the income for 4 months of rent until January of the next year. Reported the income in the year it was received. Isn't that generally how it works? (not an accountant or a tax expert)