I filed using Turbo Tax Small Business, which was purchased and downloaded. How can I find confirmation of tax filing? The IRS is saying we filed late. :(

[xmasbaby0]

There is no product called TurboTax "Small Business."  Do you have Home and Business or do you have TurboTax Business?  If you are filing a return using TurboTax Business for a multi-member LLC, partnership, C-corps or S-corps, you missed the deadline.  The deadline for business returns is not the same as the extended deadline for individual returns--which was extended to July 15, 2020

Q. Are the filing deadlines for partnerships and S-corporations whose returns were due to be filed o...

A.  Notice 2020-23 does not postpone any return filings that were due on March 16, 2020.  If a fiscal year partnership or S-corporation has a return due to be filed on or after April 1, 2020, and before July 15, 2020, that filing requirement has been postponed to July 15, 2020.  For information about additional relief that may be available to partnerships in connection with the CARES Act legislation, please see Rev. Proc. 2020-23 (PDF).

[xmasbaby0]

https://ttlc.intuit.com/community/business-taxes/discussion/what-is-the-last-date-for-filing-an-s-co...

https://ttlc.intuit.com/community/tax-planning-and-deadlines/help/tax-year-calendar-important-dates-...

[Opus 17]

Forms 1065 and 1120 for LLCs, corporations and partnerships were due March 16, 2020, and the deadline was not extended for COVID-19.

If you have never owed a penalty before, you can apply for a first-time waiver. 

https://www.irs.gov/businesses/small-businesses-self-employed/penalty-relief