How do I file for extension when I don’t know amount I paid into federal

Just take a guess.

To file an extension, please follow these steps:

1. In your return, type extension in the Search box at the top of the page.
2. Click the Jump to extension link
3. On the Need More Time to File Your Return? screen, click on the blue box, Start Easy Extension.
4. Click Continue in the pop-up window.
5. On the next screen click the File an Extension box.
6. Continue through the screens, entering the requested information.