You can report your retirement pay from Germany as miscellaneous income on line 21 page one of the 1040.
Please follow the instructions below to report your cash (check) income on line 21:
- Click Federal Taxes -> Wages & Income and scroll down to Less Common Income
- Go to the last selection, Miscellaneous Income and click Start
- Go to the last option, Other reportable income and click Start
- When it asks, "Any other reportable income?" say yes and then type in a description and the amount to report it on your tax return.