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src/Invoicing.md

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+Businesses send invoices to clients to request payment. You may want to track, eg:
+
+- how much is due to be invoiced
+- how much has been invoiced but not yet paid
+- how much has been invoiced and paid.
+
+How to record invoices and payments varies depending on whether the business
+uses the Accrual or Cash accounting method.
+
+## Accrual accounting
+
+Revenue is recorded (and taxed) in the period when the corresponding goods/services
+are provided - not at the time of payment, which usually happens after some delay.
+The expected payment is tracked as a receivable, which is a type of asset.
+
+A good time to record revenue is when the receivable is created (by sending the invoice).
+So:
+
+```journal
+2020-02-01 * (202001ab) AB Inc. | invoice for work done in january
+    revenues:consulting:ab     $-1000
+    assets:receivable:ab        $1000
+
+2020-02-15 * AB Inc. | receive full payment for 202001ab
+    assets:receivable:ab       $-1000 ;= $0  ; optional: when paid in full, assert that
+    assets:checking             $1000
+```
+
+## Cash accounting
+
+Revenue is recorded when money is actually received:
+
+```journal
+2020-02-15 * AB Inc. | receive full payment
+    revenues:consulting:ab     $-1000
+    assets:checking             $1000
+```
+
+In Cash accounting, invoices are not always tracked.
+If you want to track them, you can use equity to balance the transactions, as follows:
+
+```journal
+2020-02-01 * (202001ab) AB Inc. | invoice for work done in january
+    assets:receivable:ab        $1000
+    equity:receivable          $-1000
+
+2020-02-15 * AB Inc. | receive full payment for 202001ab
+    equity:receivable           $1000
+    assets:receivable:ab       $-1000 ;= $0
+    revenues:consulting:ab     $-1000
+    assets:checking             $1000
+```
+
+## Estimated tax
+
+If you're a freelancer in the US, eg, you may be responsible for 
+paying estimated income taxes. Here's the above transaction,
+with additional postings to track and save for tax owed:
+
+```journal
+2020-02-15 * AB Inc. | receive full payment for 202001ab and save estimated tax
+    equity:receivable           $1000
+    assets:receivable:ab       $-1000 ;= $0
+    revenues:consulting:ab     $-1000
+    equity:payable:us:2020       $150  ; estimate new tax owed, eg 15% 
+    liabilities:tax:us:2020     $-150
+    assets:checking:tax:us:2020  $150  ; save that amount (in a virtual subaccount)
+    assets:checking              $850
+```
+
+## See also
+- [invoicing entries](https://gist.github.com/simonmichael/986a65106a9db1f8bd68)
+- [Ledger Practices: Tracking Reimbursable Expenses](https://felixcrux.com/blog/ledger-practices-tracking-reimbursable-expenses)
+- https://en.wikipedia.org/wiki/Basis_of_accounting
+- https://plaintextaccounting.org/#invoicing
+- https://github.com/simonmichael/hledger/tree/master/examples/invoicing
+
+<!-- mockup for badges that could be added by a lint tool. These would cover all examples on the page. -->
+Examples tested on 2022-01-09 with:
+![](https://img.shields.io/badge/hledger-1.24.1-brightgreen.svg)
+![](https://img.shields.io/badge/ledger-3.2.1-brightgreen.svg)