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Inter-Corporate Computer & Network Services, Inc.
Invoice number format specification v1.00
An invoice number consists of a prefix (lower-case letter "i"), the
epoch (year and month), a site code, and a sequence number. This
combination supports long-term growth without creating a dependence
on constant site-to-site connectivity while also eliminating the
potential for cross-site invoice number conflicts.
prefix Lower-case letter "i" (without quotation marks).
epoch 6 digits representing the year (4 digits, which includes
the century) and the month (must always be 2 digits).
Exclusion of the day of the month is intentional because
clients sometimes need to have specific dates published
on their invoices from a different day within the month,
some invoices may be generated out of sequence by days
or weeks, and in addition to eliminating unnecessary
redundancy, the monthly granularity in epoch eliminates
a potential natural tendancy of misinterpreting invoice
numbers for the purpose of deriving the day of the month
of the billing date from an invoice number.
site-code 3 digits indicate the site code. Each site has a unique
number assigned to it, which accomodates the future need
for multiple sites to generate invoices simultaneously
without the need for active inter-site communications.
Site codes cannot imply who the creator of an invoice is
because they identify the location from which an invoice
was generated. Multiple staff may also cause invoices
to be generated from multiple sites, and recording which
staff members created specific invoices must be tracked
separately (database design and user identity are beyond
the scope of this document).
sequence 5 or more digits represent the sequence number that is
unique in series within the bounds of the epoch combined
with the site-code. At the beginning of each new epoch
the sequence commences at 00001.
More than 5 digits is also permitted to support more
than 99,999 invoices during an epoch at any given site.
The following is a graphical representation of the format using the
above-defined labels:
+--------+-------+-----------+----------+
| prefix | epoch | site-code | sequence |
+--------+-------+-----------+----------+
There are a total of 15 characters, including the prefix. The use
of the prefix is mandatory to ensure clear communication; a partial
list of prefix characters (in alphabetical order) includes:
a: Asset number (equipment, inventory items for resale, etc.)
b: Business number (assigned to clients, vendors, etc.)
c: Credit note (may be applied as payment to invoice{s})
d: Documentation (internal standards and policies, etc.)
e: Expense (invoice from a vendor)
f: Finder's fee (informal payments for business referrals)
i: Invoice
p: Proposal
q: Quotation
r: Receipt (received payment; shipping/receiving documentation)
s: Sales order (intended for pre/back-ordered products/services)
w: Work order (record of work performed prior to invoicing)
Note: To issue a refund instead of a credit, an invoice presenting
a negative amount is used to ensure consistency with the operational
style of the Knights Templar double-entry bookkeeping system (the
handling of credits in the accounting system is beyond the scope of
this document).
An example of the 232nd invoice generated during July 2013 from a
location identified by site-code "001" would be expressed as:
i20130700100232
A graphical representation of invoice number i20130700100232 could
be disected for evaluation as follows:
+---+--------+-----+-------+
| i | 201307 | 001 | 00232 |
+---+--------+-----+-------+
i Hard-coded prefix "i" indicates that this is an invoice.
201307 The year 2013 (the first 4 digits) followed by the month
of July (the final 2 digits) specifies the epoch.
001 Site code "001" indicates that this invoice was generated
by the site identified by site-code "001" only.
00232 Sequence number that is unique for the head office during
the month of July in the year 2013, also implies that
this is the 232nd invoice for the specified site's epoch.
Each site is responsible for assigning a unique and sequential
sequence number for each invoice during every epoch. This ensures
that each invoice will have a unique number among all sites, and
also supports universal audit trails throughout the organization in
a manner that is flexible and reliable.
For customer service, if there is a question about a particular
invoice that originated from a different location, staff can simply
extract the site code to quickly cross-reference who to contact.
Site codes are designated as follows:
000 Reserved (administration, and internal system use)
001 Reserved (documentation, testing, etc.)
023 Web site sales ("W" is the 23rd letter in the alphabet)
078 Head office
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Title: Invoice number format specification
Date: February 25, 2013
Version: 1.00
Author: Randolf Richardson