How to Invoice for Retainers and Recurring Work

An agency with four retainer clients at ₦500,000 a month will tell you it has ₦2,000,000 of predictable monthly revenue. Then you look at the bank account and it's empty on the 20th, because two of those invoices went out late, one client is disputing hours, and the fourth pays whenever someone in his office remembers.

Recurring revenue is only predictable if the billing is predictable. The contract gives you the revenue. The invoicing process is what turns it into cash you can plan around.

Bill in advance, not in arrears

This is the single biggest change you can make. Invoice for October's retainer at the end of September, due on the 1st, rather than invoicing on the 31st of October for work you already delivered.

Billing in arrears means you fund the entire month yourself: you pay your staff, your data, your rent, and only then do you ask for the money, and then wait out the payment terms on top. On a ₦500,000 retainer with Net 15 terms billed in arrears, cash arrives around 45 days after you started working. Bill in advance and it arrives before you start.

Customers accept this more easily than you'd expect, because it's how they already pay for rent, subscriptions, and insurance. A retainer buys reserved capacity, and reserved capacity is paid for upfront. Say that plainly in the agreement and it stops being a negotiation.

Pick a day and never move it

Fix the billing date in the contract: the 25th, every month, without exception. Not "at the end of the month," not "when the work wraps up."

A fixed date does two things. It makes your cash forecast real, because you know exactly when the money is due and when to chase if it isn't there. And it trains the customer's finance team, who batch their payment runs. An invoice that lands on the 25th every month gets slotted into the same run every month. An invoice that lands on the 25th, then the 3rd, then the 29th, is treated as a new problem each time and drifts to the back of the queue.

Say what happens to unused hours

Most retainer disputes come down to the same argument: the client used 12 hours of a 40-hour retainer and wants to know why he's paying for 40.

Settle it in writing before the first invoice. Three defensible options:

1. Use it or lose it. Unused hours expire at month end. Cleanest for you, and it's honest if the retainer is really buying reserved availability rather than a block of hours.
2. One month of rollover. Unused hours carry into the next month only, then expire. A fair middle ground that stops a client banking six months of credit and then demanding it all in December.
3. No rollover, but a floor. The retainer covers up to 40 hours, and anything under that is simply the cost of holding capacity.

Whichever you pick, name it in the agreement and repeat it as a line on every invoice ("40 hours retained, 12 used, no rollover"). The dispute you win is the one nobody has to have.

Handle overages before they happen

Decide the overage rate upfront and put a notification threshold in front of it. If the retainer covers 40 hours at ₦12,500 an hour, state that hours beyond 40 bill at ₦15,000 and that you'll flag it when usage passes 35.

The flag matters more than the rate. Nobody minds paying an overage they approved in advance. Everybody minds a ₦180,000 surprise on an invoice they thought was ₦500,000, and that surprise is what turns a routine payment into a two-week dispute while your cash sits still.

Set up payment once, not twelve times

If your customer has to re-approve a payment every month, you have twelve chances a year for it to go wrong. Push for a standing instruction, a direct debit, or a saved card on auto-charge against the fixed billing date, agreed once when the retainer starts.

Where the customer's process genuinely won't allow that (large corporates often won't), get the retainer set up as a recurring purchase order for the full term instead. A PO covering twelve months means their finance team is releasing a payment against something already approved, rather than approving something new every month.

Why retainers fix lumpy cash

If your revenue swings between a ₦4,000,000 project month and a ₦300,000 dead month, converting even part of that into retainers is the most direct fix available. It replaces a spike of cash you can't rely on with a floor you can. Two ₦500,000 retainers billed on the 25th and paid on the 1st cover your payroll before you've won a single project that month, and that changes which work you're able to say no to.

Arvalox handles the recurring side of this: it issues the invoice on your fixed billing day, applies the terms, and follows up automatically if the payment doesn't land, so a retainer that's been quietly unpaid for six weeks shows up as an overdue balance rather than a surprise at the end of the quarter. If lumpy cash is the wider problem you're solving, the cash flow versus profit post is the place to start.