Billing cycle

A billing cycle is the recurring interval at which a subscription generates an invoice — most commonly monthly, quarterly or annually. It determines when invoices are generated. It is independent of the contract term and independent of revenue recognition, and conflating the three causes a large share of billing confusion.

A single customer can hold a three-year contract term, an annual billing cycle, and monthly revenue recognition simultaneously. All three are correct; they are answering different questions.

Monthly billing

The customer is invoiced every month. It is the default for self-serve plans and for usage charges, which are billed in arrears once the month’s consumption is known. Monthly billing lowers the commitment for the buyer but means twelve collection events a year — and twelve chances for a card to fail.

Quarterly billing (quarter billing)

The customer is invoiced every three months for the coming quarter. Quarter billing is the usual compromise in B2B: the buyer avoids a large annual prepayment, and you collect cash three months ahead with only four invoices a year to chase.

A quarterly billing cycle can be anchored in two ways:

• To the contract start. A contract starting February 15 is invoiced on Feb 15, May 15, Aug 15 and Nov 15.
• To calendar quarters. Invoices go out on Jan 1, Apr 1, Jul 1 and Oct 1, and the first invoice is prorated for the part-quarter. Finance teams like this because billing lines up with quarterly reporting.

Annual billing

The customer is invoiced once a year, usually in advance. Annual billing is the norm for sales-led contracts: it brings a year of cash forward, creates deferred revenue that unwinds monthly, and is why annual-prepay discounts are worth offering. Multi-year deals are commonly billed annually rather than all up front.

Example invoice schedule

A $36,000-a-year contract starting February 15, billed in advance on each cycle:

The calendar-anchored first invoice covers Feb 15 – Mar 31: 45 of Q1’s 90 days, so $9,000 × 45 ÷ 90 = $4,500. After that the customer is on the calendar cycle for good. That partial period is plain proration.

The anchor date

Every cycle needs an anchor — the day of the month on which the invoice is cut. Two conventions exist:

• Subscription-anchored. The cycle runs from the subscription start date. A customer starting on the 14th is billed on the 14th of every period. Simple, but it spreads invoicing across all 31 days of the month.
• Calendar-anchored. Everyone is billed on the 1st, with the first period prorated. This concentrates invoicing into a single run, which finance teams generally prefer, at the cost of a prorated first invoice.

Neither is wrong. Companies with a large SMB base often prefer calendar anchoring for operational simplicity; enterprise-weighted businesses usually anchor to the contract because customers expect their own dates. Whichever you choose, add-ons bought later should be co-termed to the same cycle.

Month-end edge cases

A subscription anchored to the 31st has no anniversary in February, April, June, September or November. The standard resolution is to bill on the last day of any shorter month, but it must be defined — this is the sort of detail that surfaces as a support ticket eighteen months after launch. Bunny SaaS billing handles cycles, billing days and proration from one subscription record.