Invoicing between businesses is a three-part sequence that consumer purchases do not have. The supplier makes a claim. The buyer verifies it against what was agreed and what arrived. The buyer pays on terms agreed in advance. Every frustration on both sides comes from one of those three parts being slower or less clear than it needs to be.
The claim
The supplier issues an invoice stating what was supplied, what is owed and by when, with a unique number and, ideally, the buyer's purchase order reference. That reference is the single most useful thing on the document from the buyer's point of view, because it is what allows the claim to be checked automatically rather than investigated.
The verification
The buyer checks the invoice is theirs and is new, compares it against the order and the goods receipt, routes it to whoever has authority for that spend, and records the approval. This is where the days go, and almost always in the routing rather than the checking. Suppliers experience it as silence.
The payment on terms
Payment is deferred by agreement, usually a number of days from the invoice or the month end, and made in a scheduled run. A remittance advice tells the supplier which invoices it covered so they can allocate it. That last step removes most of the chasing calls buyers receive, and it costs nothing.
Questions people ask about how does invoicing work
Why do buyers not pay immediately?
Because business payment is deferred by agreement and conditional on verification. Paying immediately would skip the check that the goods arrived and the price was right.
What slows an invoice down most?
A missing order reference, an invoice sent to an individual rather than a monitored address, and an approver who is unavailable.
What can a supplier do to be paid sooner?
Quote the order reference, bill the address the buyer asked for, and invoice promptly. Those three remove most avoidable delay.