What's the best way for a POA to sign something?

Signing as POA is very simple and acceptable by the IRS!

Sign the name of the principal, by your name POA.

If you're also conservator and that to your title.

I sign for my Mom as Jane Doe by my name, guardian/conservator. I do not have to use POA as that is covered under my guardianship/conservatorship.

May I suggest that you have everything needed to be legally complete as a POA. The only reason I suggest is if you are using the principal's checking account, you may cause yourself a lot of legal issues. The bank should have the accounts properly labeled so you are not misusing the funds so that anyone can take you to court for not properly doing your fiduciary duties.

I'm with Ahmijoy,, I just sign POA after my name, I have not had a problem in 6 years of doing this. Sometimes I think things are just made too hard. I even get her narcotics this way with no problem.

Parent's Name, by My Name as POA

https://www.agingcare.com/articles/how-to-sign-as-power-of-attorney-for-your-elderly-parent-443408.htm

I think this might be different depending on where you live. To me it was awkward and counter-intuitive to write my mother's name in cursive as though it was a signature, I was told to sign my own name, followed by POA and my (printed) mother's name.... occasionally I was asked to put the POA before my own signature rather than after. And all the forms when mom went into long term care had a separate line for substitute decision maker, so there it really wasn't necessary.

I think that as long as all the elements are there it is just as legal any way you do it.

I’ve been told by medical personnel that a simple “POA” after my signature is fine. If there is any question, produce your signed POA contract and that should clear up any issues.