You may or may not be able to import without an actual copy of the W-2. Some require data present on the actual W-2 to be entered by the employee for verification. AND the employer must be a participant in that program and must have the W-2 ready for importing. An employer has until January 31 to furnish a W-2, so not all employers are ready. See the following 2 FAQs:
FAQ: Will I be able to import my W-2 before I get it in the mail?
https://ttlc.intuit.com/community/forms/help/will-i-be-able-to-import-my-w-2-before-i-get-it-in-the-...
FAQ: How to import or enter a W-2
https://ttlc.intuit.com/community/entering-importing/help/how-do-i-import-or-enter-my-w-2/00/26253
NOTE: Even though you may be able to efile now, by law the IRS will not issue a refund on tax returns claiming the Earned Income Tax Credit or Additional Child Tax Credit until February 15 at the earliest.
Even though it's possible to efile now, the IRS hasn't opened up return processing yet this year. So don't be in too big a hurry. The IRS doesn't open up to start processing returns until January 27. If you efile before then, your return will just sit on TurboTax servers until the IRS retrieves it on Jan. 27 (except for a few returns that are pulled early for testing purposes.) If you efile before January 27 and discover an error you need to correct, you can't retrieve the return. If the IRS accepts the return on or after Jan. 27, then the only way to correct anything is with an amended return.
Every year we see many users who efiled early only to discover a mistake, or get an extra W-2/1099 in the mail, etc., and end up with delayed refunds and having to amend a return.
