CCH exports whatever grid you’re looking at. Select everything, hit Export Grid, and you get a CSV.
Client Manager or Return Manager both work the same way. Use whichever one you normally live in.
Steps
Open Client Manager
Or Return Manager. Either.
Show everyone
Set the Quick Search filters to All and click Go.Whatever’s showing is what exports. If you only want one office, or one partner’s clients, filter now rather than trimming the file afterwards.
Select the lot
Click into the grid and press Ctrl + A.
Check your columns first
Export Grid only writes the columns you can see. If entity type, return type and tax year aren’t on the grid, add them now. Saves you keying them in on the review screen later.
Home tab, Export Grid
It’s on the Home tab.
Name it and save
Pick a folder, name the file, Save. You get a CSV.
Then bring it in
Drop the CSV into the card in Getting started, or open Clients and choose Import clients.
Pernee reads the file, proposes a name, entity type, return form and tax year for each row, and shows you the lot on a review screen. Nothing saves to your book until you hit Import.
Keep the CCH client ID in the file. Pernee holds onto it, so a later import updates the client you already have instead of creating a second one.
If your screen doesn’t match
CCH moves things around between releases, and firms set the ribbon up differently. Look for any export the grid command on whichever grid you’re in — you’ll get the same CSV. Wolters Kluwer’s support site has the current steps for your release.
Still nowhere? Any file with one row per client works, including a spreadsheet somebody keeps by hand. See Getting your client list into Pernee. 
