I usually extend due to a family K1 reporting in May each year, but this time tis different:

That K1 came in cpl weeks ago, BUT

Fido just reported a change in distribution from IGD from last Nov

This will cause a revised report to me and IRS

SO, I extended yet again

I remember a few years ago, Fido kept revising til even after 4/15

Guess this year's no different