Billed in arrears vs billed in advance
Also called: Billed in arrears, Arrears billing, Advance billing, Postpaid billing
Billed in arrears means you invoice at the end of a period for service already delivered. Billed in advance means you invoice up front. Examples inside.
Billed in arrears means the customer is invoiced at the end of a service period for what they have already received. Billed in advance is the opposite: the invoice goes out at the start of the period, before the service is delivered.
That is the whole definition. “Billing in arrears means you pay after”; “billing in advance means you pay before”. The interesting part is what each one does to your cash, your balance sheet and your billing system — and why most B2B SaaS companies end up doing both at once.
Billed in arrears: a timeline example
Take a customer on a $1,000/month platform fee plus usage at $0.05 per API call. In March they make 40,000 calls.
| Date | What happens | Billed in advance | Billed in arrears |
|---|---|---|---|
| March 1 | March service starts | $1,000 platform fee for March | — |
| March 1–31 | Customer uses the product | — | 40,000 API calls metered |
| April 1 | April service starts; March closes | $1,000 platform fee for April | $2,000 usage for March (40,000 × $0.05) |
The April 1 invoice is $3,000: April’s fee in advance and March’s usage in arrears. One subscription, one invoice, two timing rules.
When to bill in advance
In advance is the norm for recurring subscription fees: seats, platform fees, plans. The price is known before the period starts, so there is no reason to wait. The customer pays in January for January-to-December service.
When to bill in arrears
In arrears is the norm for usage-based charges, because you cannot invoice consumption before it happens. It is also common for professional services billed on time and materials, and for overages above a committed allowance.
Most B2B SaaS contracts do both at once
A typical hybrid contract bills the platform fee annually in advance and metered usage monthly in arrears. That is one subscription producing two invoice streams on two different schedules, which is exactly the structure that trips up billing systems designed around a single recurring charge. If you are building that kind of pricing, Bunny’s usage-based billing runs both on one subscription.
The cash and accounting consequences
Advance billing collects cash before the service is delivered, which creates deferred revenue — a liability on the balance sheet that unwinds as you deliver. It is also, in effect, interest-free financing from your customers, and the reason annual-prepay discounts are worth offering: trading 10–15% of contract value for a year of working capital is usually cheaper than any other funding available to a growing SaaS company.
Arrears billing delays cash by a full cycle and creates the opposite position — an unbilled receivable for revenue earned but not yet invoiced. It also carries genuine credit risk, since the service has already been consumed by the time you ask to be paid. Usage-heavy businesses manage that with minimum commitments, prepaid credits, or credit limits that trigger interim invoicing.
Billed in advance vs in arrears at a glance
| Billed in advance | Billed in arrears | |
|---|---|---|
| Invoice timing | Start of the period | End of the period |
| Typical charges | Seats, platform fees, plans | Usage, overages, time and materials |
| Cash flow | Collected before delivery | Collected a cycle after delivery |
| Balance sheet | Deferred revenue | Unbilled revenue / receivable |
| Main risk | Refunds on cancellation | Non-payment for consumed service |
Billing in advance vs in arrears in Bunny
Bunny bills recurring charges in advance and usage-based charges in arrears on the same subscription. Usage reported during a period is rated at the end of it and lands on the account's next invoice, next to the upcoming period's recurring fees.
Frequently asked questions
What does billed in arrears mean?
Billed in arrears means the customer is invoiced at the end of a service period for what they have already received or used. March’s usage is billed on April 1, not March 1.
What does billing in advance mean?
Billing in advance means the invoice is issued at the start of the period for service the customer is about to receive. An annual subscription paid on day one is billed in advance.
Is billing in arrears the same as postpaid billing?
Yes. Postpaid, billed in arrears and billed in retrospect all describe invoicing after the service is delivered. Prepaid and billed in advance describe invoicing before it.
Why are usage charges billed in arrears?
Because you cannot invoice consumption before it happens. API calls, messages sent or AI tasks completed are only known at the end of the period, so metered charges are almost always billed in arrears.
Can one subscription be billed in advance and in arrears at the same time?
Yes, and most usage-based B2B SaaS contracts are. The platform fee is billed in advance and the metered usage in arrears, often on the same invoice. Bunny handles both on one subscription — see Bunny SaaS billing.
Does billing in arrears affect revenue recognition?
It affects cash and the balance sheet, not when revenue is earned. Revenue is recognised as the service is delivered either way. Arrears billing creates unbilled revenue until the invoice is issued; advance billing creates deferred revenue.
Stop calculating this in a spreadsheet
Bunny computes SaaS metrics, revenue schedules and retention from your live billing data — because quoting, subscriptions, usage and invoicing all sit in one system.