I devote a tab in my tracking spreadsheet to federal and NYS powers-of-attorney and info authorizations -- shown in an oldish 'Snip'. I keep it next to the tab for current-year returns-in-process and the tab for current-year e-filing. Simply having the tab adjacent my hottest two reminds me to keep its contents uptodate, I believe -- the reverse of "out of sight out of mind". Like Abby, I have only virtual files now, and keep an image of the signed copy of the PoA alongside other client documents of like period.