1040 and 1041 splitting up dividends and withholding

Reassigning the withholding is not recommended as noted in your other post. You can use the following actions to assign the dividends and/or interest to the appropriate taxpayer, meaning the estate. On the individual return and on the estate return use the correct amount of taxable income based on the date of death (earnings before and after death).

Nominee Returns.  This is how the IRS knows what you are doing.

Generally, if you receive a Form 1099 for amounts that actually belong to another person or entity, you are considered a nominee recipient. You must file a Form 1099 with the IRS (the same type of Form 1099 you received).  You must also furnish a Form 1099 to each of the other owners. 

File the new Form 1099 with Form 1096 (this is a transmittal for the 1099) by mailing to the Internal Revenue Service Center for your area. (Provided on the Form 1096)

• On each new Form 1099, list the deceased as the payer and the other owner, as the recipient. On Form 1096, list the deceased as the nominee filer, not the original payer. The nominee is responsible for filing the subsequent Forms 1099 to show the amount allocable to each owner.

The forms filed with the IRS should be the red copy (use the form(s) needed) so if you don't have a color printer, go to the IRS website to fill in and print the forms here: 

• Form 1096
• Form 1099-INT
• Form 1099-DIV
• Form 1099-B