How do I obtain my IRS pin that I used last year?

The IRS PIN is good for one year. You should receive a new one every year. 

Are you referring to the 6 digit Identity Protection PIN that you received from the IRS after reporting an identity theft?  If so, the IRS sends you a new IP PIN each year in the mail which usually is sent in January.  

Or are you referring to the 5 digit PIN that is used to validate your e-filed tax return?  If so, that is a self-selected PIN that you can change each year on your own.

If you mean the IRS Identity, you get a new pin each year.  The IRS mails a CP01A letter every year. If you do not have it you can:

• Retrieve your IP PIN online at the IRS's Get an IP PIN site, or
• Call the IRS at 1-800-908-4490 to have your IP PIN mailed to you (this can take up to 21 days)

If it is the 5 digit PIN that is used to validate your e-filed tax return, then as DoninGA mentioned you can change each year on your own.

@pacejack 

How do you find or change your 2024 e-filing PIN?  The 5 digit one not the 6 digit identity protection PIN?

I am referring to the 5 digit PIN that is used to validate your e-filed tax return?  If so, that is a self-selected PIN that you can change each year on your own.

Yes, you come up with your own number.