By Paras Saini & Shubham Sharma ·
Invoice Tracking for Agencies — Managing Multi-Client AR Without the Chaos
A £8,000 monthly retainer invoice goes unpaid for 45 days. The account manager knows the client well and feels awkward chasing it. Finance doesn't have the project context to chase it credibly. No one has logged who last spoke to the client or what they said. Meanwhile the agency is paying subcontractors and media spend out of its own cash. This is the exact problem that generic invoice software doesn't solve — because agency AR has structural complications that require a different approach.
Key takeaways
- A retainer invoice that is 7 days late is a client relationship signal — treat it differently from a project invoice that is 7 days from due.
- The accounts payable contact and the project contact are almost always different people. An invoice sent to the wrong person can sit unprocessed for weeks.
- Never continue delivering on a contract where the outstanding balance is more than one billing cycle — you compound your exposure with every deliverable.
- Shared chase log per invoice is non-negotiable when multiple team members interact with the same client — duplicate chase emails are worse than no chase at all.
- Agencies carrying media spend for clients need to track when reimbursement is due separately from service invoices — a £20,000 media float at 45 days overdue is a cash flow emergency.
Why Agency Invoice Tracking Is Complex
Agency AR has several complications that generic invoice trackers often don't address. For UK-based agencies, the HMRC freelancer guidance is also relevant for sole-trader and contractor billing arrangements within an agency structure.
- Multiple invoice types per client. A single client might have a monthly retainer, a project invoice for a campaign, and an expense reimbursement all outstanding simultaneously. Each has different terms and chase logic.
- Multiple people involved in chasing. Account managers, finance staff, and founders may all contact the same client. Without a shared chase log, you end up with duplicate emails or conflicting messages.
- Large invoice values. Agency invoices are typically larger than freelance invoices. A single unpaid retainer at £8,000/month 45 days overdue is a significant cash flow problem.
- Relationship sensitivity. Account managers are reluctant to chase clients they manage — it creates awkwardness in the relationship. The chase process needs to be separate from the relationship management, or it doesn't happen.
- Media spend float. Agencies that buy media on behalf of clients carry the cost until reimbursed. Late reimbursement on a £20,000 media spend directly impacts operating cash flow.
Managing the Retainer + Project Mix
Retainers and project invoices need different tracking approaches.
Retainer invoices:
- Bill in advance (invoice for next month before the month starts)
- Set up automated monthly invoicing — send on the same date every month
- Use Net 14 or Net 7 for retainer invoices — you're providing ongoing service
- Flag immediately if a retainer invoice goes unpaid — this is the earliest indicator of a client relationship problem
Project invoices:
- Require 25–50% deposit before project kick-off
- Invoice at milestone completion — never hold invoices until the end of a long project
- Final invoice: Net 14 on delivery. Don't use Net 30 for final project invoices — the leverage reduces after delivery
Track each invoice type separately in your system. A single "Outstanding" status column can't distinguish between a retainer that's 7 days late (concerning) and a project invoice that's 7 days from due (fine).
Tracking the Right Client Contacts
At every agency client, there are two relevant contacts:
- Project contact. The marketing manager, brand lead, or director you work with day-to-day. They are not the right person to chase for payment — they typically don't approve invoices.
- Accounts payable contact. The finance team member, controller, or bookkeeper who actually processes payments. This is who your invoices should be addressed to and who you chase when invoices are late.
At your first invoice for every client, ask explicitly: "Who should I address invoices to, and is there a purchase order process?" Record both contacts in your tracker. An invoice sent to the wrong person can sit unprocessed for weeks.
Also record: purchase order requirements (many corporates won't process without a PO number), invoice format preferences (PDF, portal submission), and payment run schedule (some companies only process payments on specific dates).
The Agency Follow-Up Process
The key principle for agency chasing: separate the chase from the relationship. Account managers should not be responsible for chasing their own clients — it creates conflict of interest and emotional avoidance. Finance or admin should own the follow-up process.
The shared chase log makes this possible. When the account manager and the finance team can both see every contact attempt on an invoice, there's no duplication and no gaps.
Day 1 overdue — Finance sends standard reminder
Automated or templated email to the accounts payable contact. Invoice number, amount, due date, payment details.
Day 7 — Finance follows up, account manager informed
Finance sends second chase. Account manager is flagged — they may have context (client mentioned cash flow issues, end-of-quarter budget freeze, etc.).
Day 14 — Account manager personal contact
A personal call or email from the account manager. Acknowledges the relationship while making clear that payment is needed. If the client has a reason (dispute, cash flow), now is when you find out.
Day 21 — Pause future work
Send formal notice. Pause deliverables on any ongoing campaign. See: what to do when a client refuses to pay.
For reminder templates at every stage: reminder email templates.
AR Reporting for Agencies
Agency principals and finance leads should review AR weekly. The key metric: total outstanding by client, aged by bucket.
A weekly AR review should answer:
- What is our total outstanding balance right now?
- Which clients have invoices in the 31–60 day bucket? (These need active chasing.)
- Are there any invoices approaching 60 days? (Recovery rates drop sharply here.)
- Are any clients consistently appearing in the 30+ day bucket? (Pattern = systemic issue with that client.)
Generate your AR aging report instantly with the free AR aging report tool. For interpretation guidance: What Your AR Aging Report Is Telling You.
Invoice Tracking Tools for Agencies
InvoiceGrid — visual AR tracking for agencies
Kanban board for all outstanding invoices, per-invoice chase log (visible to the whole team), overdue flags, and AR aging. Sits alongside your accounting software. Best for agencies with 10–80 outstanding invoices. See pricing.
Chaser — automated AR for larger agencies
Multi-channel automated chasing (email, SMS, WhatsApp), per-client chase sequences, and detailed analytics. Integrates with Xero, QuickBooks, and Sage. Best for agencies with 30+ outstanding invoices.
Xero + Chaser integration
A common setup for growing agencies: Xero for invoicing and accounting, Chaser for automated AR. The integration pulls invoice data into Chaser automatically and logs all communications back to Xero.
For the full comparison: Invoice Tracking — Spreadsheet vs Software.
Ready to Track Your Invoices Visually?
Stop losing track of who owes you money. InvoiceGrid gives you a visual Kanban board, chase history, and professional email reminders.
Frequently Asked Questions
Our account manager refuses to chase their own clients — how do we fix this?+
This is the most common agency AR failure point and it is structural, not personal. The solution: separate the chase from the relationship. Finance or operations owns the follow-up process. The account manager is informed (so they have context) but does not send the chasing emails. A shared chase log per invoice makes this possible — finance can see the full contact history without involving the account manager in every decision. The account manager is only brought in directly at Day 14 when a personal touch is needed.
What payment terms should agencies use for retainer clients?+
Monthly invoicing in advance with Net 14 is the ideal structure. Billing in advance means the client pays before the month begins — zero late payment exposure on recurring revenue. Most established retainer clients will accept this. For project work: 25–50% deposit at kick-off, balance on delivery with Net 14. For large campaigns with media spend: invoice media reimbursements on a separate schedule, never let them accumulate more than one period.
A client has two months of retainer invoices outstanding — should we keep working?+
No. Pause deliverables immediately. Continuing to work against an unpaid balance compounds your exposure month over month. Send a formal overdue notice referencing your contract, request payment of the full outstanding balance or a payment plan with a first instalment within 7 days, and make continued work conditional on clearing the arrears. Most clients respond quickly when deliverables stop. Document every step of this process — if the client relationship deteriorates, you need a clear paper trail.
How do we track media spend reimbursements separately from service invoices?+
Treat each media reimbursement as a separate invoice record with its own due date and chase sequence. A common mistake is combining media costs with the monthly retainer invoice — this creates a single large invoice that is harder for the client's finance team to process and harder for you to track separately. Media reimbursements should be invoiced as soon as the spend period closes, with Net 14 terms. Track the media float (your cash out on the client's behalf) separately from your service AR.
What is the best invoice tracking tool for a growing agency?+
For agencies with 10–50 outstanding invoices at any time: InvoiceGrid provides a visual Kanban board, shared per-invoice chase log, and AR aging view alongside your existing accounting software. For larger agencies (50+ outstanding): Chaser or Kolleno offer multi-channel AR automation with Xero/QuickBooks integration and client statement generation. For all-in-one: FreshBooks or QuickBooks Online covers invoicing and basic AR. The gap all these tools leave is the shared chase log — which is what makes multi-person agency AR manageable.