Invoicing software for agencies and studios
Ten retainer clients, three project invoices, one client who always pays late, and a spreadsheet that's three tabs deep. Agency billing doesn't need its own admin day every month.
Most invoicing tools are built around sending one invoice to one client for one job. An agency runs a dozen relationships at once, most of them on a monthly retainer, some with hours that spill over the cap, and a few one-off project milestones mixed in. Bill it by hand and something eventually slips — a retainer that goes out three days late, an overage that never makes it onto the invoice, a client you genuinely can't remember has paid this month or not.
SendBilling is built for that mix. Set each client's retainer to bill itself on schedule, add extra hours or a project milestone as its own line item when they come up, and see every client's payment status — across your whole roster — in one place instead of a shared drive full of PDFs.
The billing problems specific to running an agency
A dozen clients, a dozen retainers
Client A pays $3,000 a month, Client B pays $5,500, Client C just renegotiated. Keeping every retainer amount, start date, and renewal straight in a spreadsheet falls apart the moment you pass five accounts.
Recurring billing at scale
Re-typing the same invoice for the same client every month is fine at two clients and a slog at twenty. One missed month is one client who quietly wonders if you forgot to bill — or worse, doesn't get billed at all.
Scope and hour overages
The retainer covers 20 hours; the project used 27. Ad spend crept past the agreed budget. Those extra hours and fees need to show up on the invoice as their own line item, not get absorbed for free or forgotten.
Who's actually paid?
With this many moving accounts, ‘did Client D pay this month’s retainer yet’ shouldn't require digging through email or your bank statement to answer.
How SendBilling maps to agency billing
Every feature below solves one of the problems above.
Recurring invoices per client
Set each client's billing cadence once — monthly, quarterly, whatever the contract says — and SendBilling generates and sends that invoice automatically from then on, with the right amount and your branding every time.
See recurring invoicingRetainers billed upfront, tracked separately
A retainer isn't a project invoice with a different label. Bill it as a retainer, and SendBilling keeps that pre-paid income separate from one-off project revenue in your reports, so you can see which is which at a glance.
Explore retainersMultiple businesses, one login
Running a sub-brand, a second studio, or billing through separate legal entities? Manage each as its own business — its own logo, numbering, and customers — without juggling separate accounts.
Start freePer-customer tax and currency defaults
Set the currency, tax ID, and language once for each client — a US client in USD, a UK client with VAT, an EU client in EUR — and every new invoice for that client picks up the right defaults automatically.
Start freeInvoice tracking across every client
One dashboard shows every invoice across every client as sent, viewed, paid, or overdue, so you know exactly who owes what this month without opening a single spreadsheet.
See invoice trackingWhat an agency retainer invoice looks like
A real month for a client on a retainer with ad-spend management and an overage — retainer, management fee, extra hours, and a project milestone, all on one invoice.
Invoice #AG-0142
Bright Path Marketing → Northgate Dental Group
| Description | Qty / Rate | Amount |
|---|---|---|
Monthly retainer — Marketing services June 2026 · SEO, content, and social management | 1 | $4,000.00 |
Ad-spend management fee 15% of $10,000 managed ad spend | 15% | $1,500.00 |
Extra hours over retainer 6 hrs beyond the 20-hr monthly cap | 6 × $150.00 | $900.00 |
One-off project milestone Website redesign — Phase 2 delivery | 1 | $2,500.00 |
| Subtotal | $8,900.00 | |
| Tax (8%) | $712.00 | |
| Total due | $9,612.00 | |
The retainer line regenerates every month on its own schedule; the overage and milestone lines are added only when they apply. Want to build one like this right now? Try the free invoice generator or start from our marketing agency invoice template.
From estimate to retainer to paid
A new client rarely starts on a retainer. You send an estimate for the first month or the discovery project, they approve it online, and it converts into an invoice in one click — no re-typing the scope you already agreed on. Once the relationship settles into an ongoing retainer, switch that client to a recurring invoice and SendBilling takes over sending it, month after month, on the date you set.
Every invoice — retainer, overage, or one-off milestone — still shows its own status. If a client's retainer invoice sits unpaid past the due date, it shows up as overdue in invoice tracking right alongside every other client, instead of getting lost in a month-end reconciliation you have to do by hand.
SendBilling doesn't hold your money
We don't process payments or take a cut. Connect Stripe, Wise, or your own bank link, and the Pay button on every invoice sends clients straight to your provider — your retainer income lands in your account, not ours.
Stop rebuilding the same retainer invoice by hand.
Free and unlimited during early access — no credit card required to try it.
Agency invoicing FAQ
Can I bill a monthly retainer and a one-off project for the same client?
Yes. Set up the retainer as a recurring invoice on its own cadence, and add one-off project or milestone invoices separately whenever they come up. SendBilling tracks retainer income and project income as distinct types, so your reports don't blur the two together.
How do I bill for hours over the retainer cap?
Add an extra line item — for example "Extra hours over retainer, 6 hrs at your overage rate" — to that month's invoice, or send it as a separate one-off invoice if you'd rather keep the retainer invoice clean. Either way it's a normal line item, not a special billing type.
Can each client have their own currency and tax setup?
Yes. Set a currency, tax ID, and language per customer once, and every invoice you create for that client — recurring or one-off — uses those defaults automatically, which matters once you're billing clients in more than one country.
Does SendBilling handle running the agency and a separate studio brand?
Yes. Create a second business inside the same account for a sub-brand or a separate legal entity, each with its own logo, invoice numbering, and customer list, and switch between them without a second login.
Is this free for agencies right now?
Yes. SendBilling is in early access, so recurring invoices, retainers, multiple businesses, and invoice tracking are all free and unlimited on every plan. A Free plan, a $4.99/mo Pro plan (first month $1), and a $19.99 one-time Lifetime plan launch later — early users keep what they're already using.
Updated July 2026Recurring invoicingInvoice trackingPricing