I wrote this for interest but should work for dividends too. Whoever's ssn is on the 1099 enters the whole amount on their return. Then after you enter it, on the next page it will ask
Tell us if any of these uncommon situations Apply and pick the first one, We need to adjust the taxable amount.
Then on the next page fill in the amount as a POSITIVE number and pick the first reason "I received all or part of this for someone else".
Then on the other person's return you enter it as a 1099Div.
