What it means
The index compares two things: the total amount that was available to collect, and the amount that was genuinely collectable but is still outstanding. Everything the business started with in receivables, plus everything it sold on credit during the period, forms the pool.
What remains overdue at the end is the shortfall. The reason finance teams prefer this measure to days sales outstanding is that it isolates the collections effort from sales growth.
Days sales outstanding rises simply because a business sold more late in the month, which makes a strong collections team look weak. The index adjusts for this by excluding invoices that are not yet due from the denominator.
It is normally calculated monthly and tracked as a trend rather than a single reading. Most businesses treat anything above 80% as reasonable and anything above 90% as strong, though the right target depends on customer mix; a firm selling to large corporates with 60 day terms will look different from one selling to small retailers.
What matters is the direction and the explanation behind any movement. Interpreting a fall requires care because the causes sit all over the business.
A dip can come from a genuine collections problem, but it can equally come from disputed invoices, incorrect billing, a customer in distress, or sales agreeing extended terms without telling anyone. Using the index as the opening question in a monthly review, rather than as a verdict, is the productive approach.
The main limitation is that a single large account can dominate the number. One disputed $400,000 invoice in a $2 million ledger will drag the index down regardless of how well the team handles the other hundred accounts.
Sensible reporting therefore shows the index alongside an ageing profile and a list of the largest overdue balances.
In practice
Real-world examples.
Example
A commercial cleaning company sees its index fall from 92% to 76% in a single month. Investigation shows one facilities management client withheld payment pending a service credit, not a general slide in collections. The credit controller resolves the dispute and the index recovers the following month.
Example
A software vendor moves from annual invoicing to monthly billing and watches days sales outstanding jump, which alarms the board. The collection effectiveness index stays flat at 89%, showing the change was a billing timing effect rather than a collections failure. The finance director uses the index to calm the discussion.
Example
A building supplies merchant sets a bonus for its credit team tied to keeping the index above 85% for two consecutive quarters. The team starts calling customers three days before due dates rather than fourteen days after, and the score climbs from 79% to 88%. Average bank borrowing falls by roughly $200,000 as a result.
Think of it
“CEI shows how effective you are at collecting what you're owed-your collection success percentage.
Formula
Calculation
Collection effectiveness index = (Beginning receivables + Credit sales - Ending total receivables) / (Beginning receivables + Credit sales - Ending current receivables) x 100
A distributor starts the month with $800,000 in receivables and makes $1,200,000 of credit sales. At month end total receivables are $700,000, of which $620,000 are current, meaning not yet due, and $80,000 are overdue.
Numerator = $800,000 + $1,200,000 - $700,000 = $1,300,000 collected.
Denominator = $800,000 + $1,200,000 - $620,000 = $1,380,000 that could have been collected.
Index = $1,300,000 / $1,380,000 x 100 = 94.2%.
The team collected $1,300,000 of the $1,380,000 that was genuinely available, leaving $80,000 overdue. A score of 94.2% is strong performance.Case study
Seen in the real world.
The following is an illustrative and entirely fictional example. Merridale Fixtures, an invented commercial furniture supplier, had $3.4 million of receivables and a persistent cash squeeze despite growing sales. Its days sales outstanding of 58 days looked poor, but nobody could tell whether the problem was the collections team or the sales terms.
Calculating the collection effectiveness index gave a clearer answer. The score sat at 71%, meaning almost a third of genuinely due money was going uncollected each month, while the ageing report showed the overdue balances were concentrated in fifteen accounts sold by two representatives who had quietly offered 90 day terms.
Merridale tightened its credit approval process, moved those accounts to standard 30 day terms and gave the credit controller authority to place accounts on hold. Within four months the index reached 89% and the overdraft balance fell by $480,000. In this fictional case the index did not fix anything by itself, but it pointed the management team at the right fifteen customers.
Watch out
Common mistakes.
- Including invoices that are not yet due in the denominator, which understates the score and punishes a team for money nobody expected to have collected.
- Using total sales instead of credit sales, so cash and card transactions inflate the pool and distort the result.
- Reading a single month in isolation, when one large disputed account can move the index by ten points without any change in collections behaviour.
Questions
People also ask.
What is a good score?
Above 80% is generally acceptable and above 90% is strong, but the right benchmark depends on your customer mix and payment terms.
How does this differ from days sales outstanding?
Days sales outstanding measures how long money takes to arrive, while this index measures what proportion of collectable money actually arrived, so it is far less distorted by sales growth.
How often should it be calculated?
Monthly is standard, and weekly is worth doing in businesses with tight cash where early warning matters more than precision.
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