Johnny.Decimal filing

Give every kind of document in your practice a short number, like 21.01 Bank statements, and use that same number everywhere: your file folders, your email labels, and your notes.

Johnny.Decimal is a free, well-documented filing system created by Johnny Noble. This page covers how it works and how I lay it out for my solo practice. The full method is at the source:

johnnydecimal.com: start with the Introduction, then Areas and categories, IDs, The JDex, and Saving files
Forum, where people share their systems
Products, paid ready-made systems (including one for small-business admin) and courses; the free documentation is enough to build your own

How it works

Three levels, never more than ten choices at any of them.

Level	Looks like	What it is
Area	`20–29 Finances`	A broad part of your life or business. At most ten, numbered in tens.
Category	`21 Banking & bookkeeping`	A drawer inside an area. At most ten per area (21 through 29).
ID	`21.01 Bank statements`	A folder that holds files: the category number, a decimal point, then 01, 02, 03…

The rules:

Nothing goes deeper than an ID. No subfolders; a crowded ID is usually two IDs.
No more than ten at any level, so you can find anything in three steps.
Numbers don't move. Numbered folders sort the same everywhere, and "it's in 21.01" is quicker than a path.
Same number everywhere: the folder on your drive, the label in your email, and the heading in your notes.

The JDex: your index

The JDex is a list of every ID, usually in a notes app: one entry per ID with its number, name, and where its stuff lives (folder, email label, app). In the creator's words, "The index is your Johnny.Decimal system." It's where you decide where something goes before you file it, and what stops you creating 21.07 Bank stuff next to 21.01 Bank statements.

A sample layout for a solo practice

An illustration only; build yours from the documents you actually have.

10–19  Practice administration
       11  Licenses & credentials
           11.01  State license ([State])
           11.02  NPI, CAQH & registrations
           11.03  Malpractice insurance
           11.04  CE certificates
       12  HIPAA & compliance
           12.01  Policies & procedures
           12.02  Security risk analysis
           12.03  Vendor BAAs
           12.04  HIPAA process log
       13  Software & vendors
           13.01  EHR account & settings
           13.02  Email & cloud (Workspace / Microsoft 365)

20–29  Finances
       21  Banking & bookkeeping
           21.01  Bank statements
           21.02  Monthly close
           21.03  Card processor reports
       22  Taxes
           22.01  Quarterly estimates
           22.02  Annual return & CPA correspondence
       23  Expenses & receipts
           23.01  Receipts
           23.02  Mileage log

30–39  Marketing & referrals
       31  Directories
           31.01  Psychology Today
           31.02  [Second directory]
       32  Referral partners
           32.01  Referral tracker
           32.02  Letters & one-pagers
       33  Website
           33.01  Site copy & images
           33.02  Domain & DNS records

Client records aren't here. They live in your electronic health record (EHR) system, covered by a business associate agreement (BAA). Keeping this tree to the business side is also what makes it safe to use with a general-purpose AI assistant.

Personal admin can share the tree, as an area like 40–49 Home.

Why it pairs well with AI

A numbered tree is easy for an assistant to work with (see using AI to run the practice):

"File this in 23.01" can't be misread the way "put it with the other receipts" can.
The JDex is its map, including when to ask you instead of guessing.
Scans come out clean: it reads each one, names it 2026-03-14 [Vendor] - [What it is].pdf, and proposes an ID for you to approve.
Routines point to fixed places: "the monthly close reads exports from 21.01 and writes its summary to 21.02."

Getting started

Read the Introduction. It takes 10 minutes.
List the kinds of things you keep, from your downloads folder, desktop, and email. Don't sort yet.
Group them into areas and categories on paper, three to five areas to start.
Start the JDex, one note per ID, before you create any folders.
Make the folders and move things in one category at a time, starting with what you hunt for most (usually finances).
Match your email labels to the same numbers as you go.
Expect to adjust for a month. After that, a new document takes seconds to place.