Founder and editor
Md Sayful Islam is a web developer from Bangladesh who has built and run websites since 2017. He also runs Themeve, a store that sells WordPress themes and plugins, some of them by subscription. He researches every Billing Model guide from primary sources such as accounting standards, card-network rules and platform documentation, and links to them in each article.
A credit memo example with every field filled in, plus when to issue one, how the credit is applied, the basic journal entry and how it differs from a refund or a debit note.
10 min read
Setting up recurring payments means getting permission once and collecting on a schedule. Here are the six decisions a business has to make, in order.
10 min read
How freemium pricing works: where to draw the line between free and paid, how it differs from a free trial, and a worked break-even conversion example.
9 min read
The net revenue retention formula shows whether revenue from your existing customers grew or shrank over a period. Here is the calculation, with an eight-customer example.
9 min read
Chargeback prevention means fixing the reason behind each dispute: fraud, an unclear descriptor, a forgotten renewal, a delivery problem or a slow refund.
9 min read
A past due invoice is one that is still unpaid after its due date. Here is a follow-up sequence by days overdue, what each message should contain, and the options if nothing works.
10 min read
A failed payment is a charge the customer's bank declined or sent back. Here is why it happens, when a retry is allowed, and what to do in order.
10 min read
Flat-rate pricing charges every customer the same fixed price for the same plan. Here is how it works, a worked margin example and when it stops working.
9 min read
The monthly recurring revenue formula sums every paying customer's subscription fee, restated per month. See what to include, the five movements and a worked month.
9 min read
Interchange plus plus pricing (IC++) bills card payments in three visible parts: interchange, scheme fees and the acquirer's markup. Here is how to read it and who it suits.
10 min read
Late fees on invoices are either a flat charge or interest on the overdue balance. Here is how to calculate each, with worked examples and sample wording.
10 min read
A billing period is the stretch of time one bill covers. See how it differs from the billing cycle, billing date and due date, with worked proration.
9 min read
