What it means
Before Base I, approving a card payment above a set floor limit meant a telephone call from the shop to the bank, which could take several minutes. Base I replaced that with an electronic network that routed an approval request from the merchant's bank to the cardholder's bank and returned an answer automatically.
The name came from the BankAmericard service exchange that preceded the Visa brand. Its contribution was speed and standardisation: one message format, one network, and a response fast enough that the customer stayed at the counter.
Crucially, an authorisation is only a decision, not a payment. Base I answered the question of whether funds or credit were available and reserved the amount, while Base II later collected the day's transactions in a batch overnight and worked out what each bank owed the others before any cash actually moved.
This two-stage structure matters to any business that takes card payments, because it explains several everyday puzzles. An approved authorisation can still fail to settle, a reserved amount can sit on a customer's statement as pending for days, and the figures in a merchant's till report will not match the bank credit exactly.
The modern descendants of these systems carry far more than an approval code, including fraud scoring and tokenised card numbers. The architectural split remains the same, though, which is why merchant terms still distinguish between authorisation rates and settlement timing.
Base I also introduced the idea of a stand-in decision, where the network answers on the issuer's behalf if the issuer's own systems cannot be reached. That concept survives today and explains why a payment can be approved even when a bank is offline, with the risk of that approval sitting with whoever set the stand-in rules.
In practice
Real-world examples.
Example
A coffee chain notices that card approvals drop sharply at one branch during the morning peak. The problem turns out to be a slow internet line causing authorisation requests to time out, so the terminal falls back to offline rules and declines higher amounts. Upgrading the line restores the approval rate and recovers several hundred dollars of lost sales a week.
Example
An online retailer places a $1 authorisation on a new card to confirm it is valid before shipping an order. The $1 is never settled, but it appears as a pending item on the customer's statement for several days and generates a support query. The retailer adds a line to its checkout page explaining the temporary hold, and the queries largely stop.
Example
A hotel pre-authorises $400 against a guest's card at check-in to cover incidentals. The final bill is $265, so the hotel settles $265 and releases the balance, which takes a few days to disappear from the guest's available credit. The guest complains about the missing $135, and the front desk can only explain the timing rather than speed it up.
Case study
Seen in the real world.
Riverbend Garden Centres is an illustrative, fictional chain of six stores whose finance manager cannot reconcile card takings to the bank. Daily till reports show roughly 2% more card revenue than the amounts credited by the acquiring bank.
In this fictional example the manager learns the authorisation and settlement distinction and rebuilds the reconciliation in two steps: authorised amounts from the terminal report, then settled amounts from the acquirer file. The gap resolves into three causes, namely authorisations that were never captured at the end of a shift, partial refunds processed the following day, and a small number of genuinely declined transactions recorded as sales by staff.
The illustrative fix is procedural rather than technical. Riverbend adds an end-of-day capture check to the closing routine and reconciles settled amounts only, which removes the recurring unexplained difference.
Watch out
Common mistakes.
- Treating an authorisation code as confirmation that the money has arrived, when it only confirms the payment was approved and reserved.
- Reconciling card sales against authorised totals rather than settled totals, which guarantees a permanent difference.
- Assuming a pending charge on a customer's statement means they have been billed twice, when it is usually an authorisation waiting to drop off.
Questions
People also ask.
What is the difference between Base I and Base II?
Base I handled real-time authorisation decisions, while Base II handled the later clearing and settlement of the approved transactions in batches.
Does Base I still exist under that name?
The function lives on inside modern card networks, but the original system names are now mainly historical references used to explain how authorisation and settlement came to be separated, and why merchant pricing still treats them as two different services.
Why would an approved transaction still not reach my bank account?
Because authorisation and settlement are separate steps, so an approval that is never captured, or is reversed, never turns into a payment.
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