"If you want to e-file, the easiest approach is to enter the foreign pension income on Form 1040, Line 21 "Other income" as "Foreign pension." You won't need a Payer ID, state or zip code with this approach.
The IRS wants the pension reported as income - unless your pension receives special tax treatment, it is perfectly OK to report it as "Other Income".
To make entries on Line 21, go to the Other Reportable Income interview, the very last interview in Wages and Income (Federal Taxes tab > Wages & Income category > Less Common Income subcategory > Miscellaneous Income sub-subcategory).
In TurboTax Online, enter "other reportable income" in the Search Box and then select "Jump to Other Reportable Income".
If you choose this way, then you won't have to create a substitute Form1099-R by filing Form 4852 and you won't encounter e-file errors over the Payer ID. However, the end tax result (in terms of United States tax rate and amount assessed) will be identical under both methods.
(If you already have a substitute 1099-R and Form 4852 in your tax file, See: How do I delete forms in TurboTax Online? to remove them. After deleting these forms, log out of the program. When you log back in, use the Delete a Form tool (List of Forms in My Return) to confirm they have been removed from your return).
Your other option is to prepare a Substitute Form 1099-R and a Form 4852 to report that foreign pension on your tax return.
In the Retirement Income interview for Pension Plans (Form 1099-R), check "I need to prepare a substitute Form 1099-R" and follow the instructions in the interview.
