The stimulus depends on how it was paid. If the IRS recognized that you were joint filers, then they would have paid $2400 and $1200, and you would report half each. If your income was more than $150,000 so that the stimulus was reduced, you would still report half each. However, if only one of you received a payment, then it might have been $1200 to one spouse and zero to the other. Look at your letters (form 1444 and 1444-B) that the IRS sent.
Interest income on joint investments can be divided any way you choose.
If you live in a community property state, you would divide the interest 50/50, but you would also have to divide the wages and UEC 50/50 in most cases. Separate returns in a community property state often require professional help.
