There seems to be some interest, so here’s a very quick example of what happens when you buy a 4-week $1,000 T-Bill.
1) Open an account at TreasuryDirect, link up checking/savings account.
2) Login, and select your amount and maturity date ($1,000)
3) You must schedule the purchase before Noon EST on the auction date (Tuesdays), otherwise you are pushed to next week.
4) Auction occurs on Tuesday, and on Thursday the discounted amount ($99x.xx) is taken out of your account.
5) 28 days later, also on a Thursday, $1000 is put back into your account if you choose so. If there is a holiday both the purchase and maturity dates are moved together. I’ll do a better example later.