As portrayed in the film Apollo 13, astronaut Jack Swigert forgot to file his taxes:
JACK SWIGERT: Well uh, if anyone from the IRS is watching, I forgot to file my 1040 return and I meant to do it today but...
SY LIEBERGOT (EECOM - WHITE): That's no joke! They'll jump on him!
In real life, when did Jack Swigert realize that he forgot to file his taxes? A complete answer will include the calendar date, mission time, and the relevant dialogue (especially the funny parts).
It's worth noting that in 1970, the deadline to file taxes was April 15.
This question is part of a series honoring the 50th anniversary of Apollo 13, "NASA's finest hour".