HOW TO ATTACH A FORM 2439 TO 1041

[George4Tacks]

I think you really want to know HOW TO INPUT 2439 ON A 1041.

When all else fails look at the back of the form for:

Instructions for the Shareholder
Section references are to the Internal Revenue Code.
Reporting Information
Shareholder’s identifying number. For your protection, Form 2439
may show only the last four digits of your identifying number (social
security number (SSN), etc.). However, the RIC or REIT has reported
your complete identifying number to the IRS.
Box 1a. This amount is your total undistributed long-term capital
gain from your regulated investment company (RIC) or real estate
investment trust (REIT).
Report the total amount as a long-term capital gain on the
appropriate Schedule D. For example, individuals report this amount
on line 11, column (h), of Schedule D (Form 1040). Estates and
trusts report this amount on Schedule D (Form 1041).
Corporate shareholders report this amount in Part II of Form
8949. See Form 8949, Schedule D (Form 1120), and the related
instructions for details.
If there is an amount in box 1b, 1c, or 1d, special instructions
apply for entering those amounts on the appropriate Schedule D.
See Undistributed Capital Gains in the Schedule D (Form 1040)
and Schedule D (Form 1041) instructions.
Box 1b. This amount is the unrecaptured section 1250 gain.
Individual filers report this amount on line 11 of the Unrecaptured
Section 1250 Gain Worksheet in the Schedule D (Form 1040)
instructions for 2021 or the applicable line of the worksheet in the
instructions for the current year. Estates and trusts use this amount
to complete the Unrecaptured Section 1250 Gain Worksheet in the
Schedule D (Form 1041) instructions.
Box 1c. This amount applies to the portion of the amount in box 1a
attributable to a section 1202 gain (sale of qualified small business
stock). Individual filers, see Exclusion of Gain on Qualified Small
Business (QSB) Stock in the Schedule D (Form 1040) instructions.
Estates and trusts, see Exclusion of Gain on Qualified Small
Business (QSB) Stock (Section 1202) in the Schedule D (Form 1041)
instructions.
Box 1d. This amount is the collectibles gain (28% rate gain) portion
of the amount in box 1a. Individual filers enter this amount on line 4
of the 28% Rate Gain Worksheet in the Schedule D (Form 1040)
instructions for 2021 or the applicable line of the worksheet in the
instructions for the current year. Estates and trusts use this amount
to complete the 28% Rate Gain Worksheet in the Schedule D (Form
1041) instructions.
Box 2. This amount is the tax paid by the RIC or REIT on the
undistributed long-term capital gains shown in box 1a. You can
apply for a refund or credit of this tax as follows.
(Continued on the back of Copy C)

Instructions for the Shareholder (Continued)
Individuals, nonresident aliens, and estates and trusts. See
line 13a of Schedule 3 (Form 1040) of the 2021 form or the
applicable line on the current year form, or Schedule G, line 16a of
Form 1041 of the 2021 form or the applicable line on the current
year form, and the related instructions.
Corporations (other than S corporations). See Schedule J, line
20a of Form 1120 of the 2021 form or the applicable line on the
current year form, or line 5f of Form 1120-F of the 2021 form or the
applicable line on the current year form, and the related instructions.
All other corporations report this amount on the line designated as
“Credit for tax paid on undistributed capital gains.”
S corporations and partnerships. See the Specific Instructions
for Schedules K and K-1, Part III (Forms 1120-S and 1065) for
details on reporting each item to the shareholders and partners.
Exempt organizations and certain trustees. See the
Instructions for Form 990-T if it is filed by:
1. Organizations exempt from tax under section 501(a) filing Form
990-T to claim their refund of income tax paid on undistributed
long-term capital gains, or
2. Trustees for individual retirement arrangements (IRAs)
described in section 408 (including accounts described in section
408(h)) filing a single composite Form 990-T to claim the refund
referred to above.
Nominees. If you are not the actual owner of the shares for which
this form is issued, you must do the following.
1. Complete Copies A, B, C, and D of Form 2439 for each owner.
The total undistributed long-term capital gains entered in box 1a;
the amounts entered in boxes 1b, 1c, and 1d and the tax shown in
box 2 on the Form 2439 for each owner must agree with the
amounts on Copy B that you received from the RIC or REIT.
2. Enter your name as “Nominee” and your address in the block
for the RIC’s or REIT’s name and address, and the RIC’s or REIT’s
name and address in the same block.
3. Write “Nominee” in the upper right corner of the Copy B you
received from the RIC or REIT and attach it to the Copy A you
completed.
4. File the Copy B you received (with an attached Copy A) with
the Internal Revenue Service Center where you file your income tax
return.
5. Give the actual owner Copies B and C of the forms you
complete.
6. Copy D is to be maintained by the RIC or REIT.
A nominee has 90 days after the close of the RIC’s or REIT’s tax
year to complete items 1 through 5 above. However, a nominee
acting as a custodian of a unit investment trust described in section
851(f)(1) has 70 days. A nominee who is a resident of a foreign
country has 150 days.

BTW - all caps are not encouraged as they are hard to read. 

[BobKamman]

Use a stapler.  Paper clips come loose.

If you're asking where to input the tax withholding, it's on Page 3, Schedule G, Line 16:

Line 16—Credit for Tax Paid on Undistributed
Capital Gains
Attach Copy B of Form 2439, Notice to Shareholder of
Undistributed Long-Term Capital Gains.

Or is this a "how to e-file" question?  Same way you attach images of other documents.