Proforma, Interim, Recurring: Which Invoice Type Do You Need?
A printing business quotes ₦1,200,000 for a corporate job. The client says "send me an invoice so I can raise a PO." The printer sends a normal invoice, books ₦1,200,000 as a receivable, then watches it sit in the overdue column for six weeks while nobody at the client feels any urgency, since the work hasn't even started.
The printer sent the wrong document. Using the right invoice type is one of the cheapest ways to get paid on time, and there are only a handful worth knowing.
Proforma invoice: a quote wearing an invoice's clothes
A proforma invoice looks like an invoice but isn't one. It's a commitment in invoice shape: this is what we'll supply, this is what it will cost, this is what you'll owe when we do. It carries no invoice number in your sequence, it isn't a demand for payment, and it should never enter your books as revenue or your aging report as a receivable.
You send one when the buyer needs something official to act on before the job exists. Corporate clients often can't raise a purchase order against a scrappy email quote. Some customers need one to release an advance payment, and importers need one for customs and letters of credit. Send a proforma, let them raise the PO, then issue the real invoice when you deliver.
Standard invoice: the one that actually asks for money
The standard invoice (sometimes called the final invoice) is the legal request for payment. It carries a sequential number, an issue date, a due date, your terms, and the exact amount owed. This is the document that creates a receivable, starts the clock, and gives you something to chase.
One thing worth getting right here: write the due date on it, not just the term. Customers pay dates, not jargon. If you're not sure what terms to put on it, we covered Net 30, Net 15, and what to actually offer.
Interim invoices: getting paid while the job runs
A contractor doing a ₦5,000,000 office fit-out over three months cannot wait until handover to see a naira. If they do, they're funding the client's project out of their own pocket, paying for materials and labour up front against a payment that lands twelve weeks later.
Interim invoices (also called progress invoices) fix that. You bill against milestones or percentage completion: 30% on mobilisation, 40% at second fix, the balance on handover. Each interim invoice is a full invoice, with a real number, real terms, and a real due date, so it can be tracked and chased like any other.
At the end you issue a final invoice that reconciles everything: the full contract value, less what has already been invoiced and paid, leaving the closing balance. Agree the milestone schedule in writing before work starts. A milestone that isn't defined is a milestone the client will dispute the moment you bill it.
Recurring invoices: the retainer trap
An agency on a ₦450,000 monthly retainer sends the same invoice on the same day every month. That's a recurring invoice, and it should be automated, because typing it out by hand twelve times a year is how you end up sending it late, or not at all.
The risk with recurring invoices is that they go invisible. Both sides stop reading them. You assume it's being paid because it always has been, and one day you look up and three months have gone unpaid because a card expired or the client's finance lead changed. Recurring billing needs the same aging discipline as everything else, and an aging report is what surfaces it.
Credit notes and debit notes: fixing what you already sent
You overcharged a distributor by ₦80,000. Do not edit the invoice, and do not delete it. A sent invoice is a record, and quietly rewriting records is how you lose an audit trail and a customer's trust in the same afternoon.
Issue a credit note instead. It reduces what the customer owes, references the original invoice, and leaves both in the history where they belong. Credit notes handle overcharges, returns, cancelled work, and goodwill discounts.
A debit note works the other way and increases the amount owed. You use it for extra work done outside scope, or when you undercharged and both sides agree the invoice was short. Buyers also issue debit notes to flag a shortfall in a delivery, so if a customer sends you one, it's a claim, not a payment.
Picking the right one
The choice comes down to when the money should move. Nothing delivered yet but the buyer needs paperwork to commit: proforma. Work delivered: standard invoice. Long job that would drain your cash before completion: interim invoices against milestones. Same fee every month: recurring. Something wrong on an invoice you already sent: a credit or debit note, never an edit.
Where Arvalox fits
Arvalox handles these as distinct documents rather than one generic template: proformas that convert into a real invoice once the work is confirmed, recurring schedules that issue themselves on the day they're due, and credit notes that adjust a customer's balance without touching the original record. Everything that becomes a genuine receivable then flows into the same aging view, so a forgotten retainer or an unpaid milestone shows up next to everything else you're owed.