did the partnership file an extension? the return was originally due 3/15 without one and 9/15 with it. late filing penalties are about $200/month/partner
it's up to the IRS to bill you if you filed late. then you can request abatement of penalties if this is the first time you filed late. penalty abatement is at the discretion of the IRS
you can't do a partnership return online. you need Turbotax Business which can only be installed on a full windows PC.
https://turbotax.intuit.com/small-business-taxes/
also available through online retailers but be careful some are not legit.
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