Where can I find the Filer's federal ID no.?

If you're entering an income document into TurboTax, the Federal ID Number is usually at the top left.

 

It may be worded a bit differently, such as 'Tax ID Number' or 'Federal EIN' or 'Payer ID Number'. It's a number formatted like xx-xxxxxxx.

 

Here's more info on Federal ID Number.

 

@lewis-liz-ann