Every agency owner knows the feeling. The project is delivered, the client is happy, and then the invoice sits unpaid for weeks. You send a follow-up email that gets buried. Then another. Your bookkeeper asks about the outstanding balance. Meanwhile, your own bills keep arriving on time.
This pattern is not a client problem — it is a process problem. Agencies that rely on email-based invoicing and manual payment tracking lose an average of 15 hours per month on billing administration alone. The real cost is not just time: late payments strain cash flow, awkward payment conversations damage client relationships, and scattered financial data makes it impossible to forecast revenue accurately.
A client billing portal solves this by giving your clients a single place to view invoices, make payments, manage subscriptions, and download receipts — on their own terms, without involving your team. This guide walks you through exactly how to set one up for your agency in 2026, what features matter most, and how to migrate from your current billing process without disrupting client relationships.
Why Agencies Struggle with Client Billing
The agency billing problem is structural, not personal. Most agencies start with simple tools — a spreadsheet, a PayPal link, maybe QuickBooks — and never upgrade their process as the business grows. Understanding why this breaks down helps you build something better.
Email-based invoicing feels simple, but it creates invisible costs that compound with every new client. When you send an invoice as a PDF attachment, you lose visibility the moment it leaves your outbox. Did the client open it? Did it land in spam? Are they disputing the amount or simply too busy to process it?
Research from Atradius shows that 48% of B2B invoices in Europe are paid late, with the average delay running 15 days past terms. For an agency billing €10,000 per month across ten clients, that delay means roughly €5,000 is perpetually locked in receivables — money you have earned but cannot spend.
The follow-up cycle makes it worse. Each overdue invoice requires a reminder email, then a second reminder, then an awkward phone call. Your team spends hours on work that generates zero revenue and strains the very relationships your agency depends on.
Agencies with 5-10 clients can manage billing manually. At 20+ clients with mixed billing models — some on retainers, some per-project, some with deposits — the complexity outpaces any spreadsheet.
Common failure points include retainer renewals that slip through the cracks, deposit invoices sent too late to protect against scope creep, inconsistent payment terms across clients, and no single view of who owes what. Each of these failures costs real money, and the compound effect is substantial.
Your clients are B2B professionals who manage their own vendor payments. They expect the same self-service experience from you that they get from their SaaS tools, hosting providers, and other business services.
A 2025 McKinsey survey found that 70% of B2B buyers prefer digital self-service over speaking with a sales or support representative. This preference extends to billing. Clients want to log in, see their balance, pay with one click, and move on. They do not want to email your accounts team to request a copy of last month's invoice.
What a Client Billing Portal Actually Does
A client billing portal is more than an online payment page. It is a centralized hub where every financial interaction between your agency and its clients happens — automatically, transparently, and on demand.
When a client logs into their billing portal, they see a dashboard showing their current balance, recent invoices, active subscriptions, and payment history. From this single view, they can pay an outstanding invoice with one click, download any historical invoice or receipt, update their payment method (credit card, SEPA, iDEAL), view upcoming subscription renewals, and request changes to their plan.
This self-service capability eliminates the back-and-forth emails that consume your team's time. When a client needs a receipt for their accountant, they download it themselves. When their card expires, they update it without your involvement. When they want to see what they owe, they check the portal instead of emailing you.
On your side, the billing portal provides a complete view of your revenue. You can see which invoices are outstanding and for how long, track payment trends across your client base, identify clients at risk of churning based on payment behavior, forecast monthly and quarterly revenue with confidence, and automate follow-ups for overdue balances.
This visibility transforms billing from a reactive chore into a strategic tool. When you can see that a long-term client has started paying later and later, you can address the issue proactively — before it becomes a collections problem.
Not every billing portal feature is equally important. Based on how agencies actually bill their clients, these capabilities deliver the most value.
Recurring billing and retainer management. Most agencies have some form of recurring revenue — monthly retainers, quarterly strategy reviews, annual contracts. Your portal should handle these automatically: creating invoices on schedule, collecting payment, and notifying you only when something fails.
Deposit and milestone billing. Project-based agencies need to collect deposits before work begins and bill milestones as deliverables are completed. A good portal lets you configure deposit percentages and create milestone payment schedules that clients can track.
Multi-currency support. Agencies working with international clients need to invoice in the client's preferred currency. Your portal should handle currency conversion and display amounts in the currency the client expects to pay.
Automated payment reminders. The portal should send reminders automatically when invoices approach their due date and escalate communication when they become overdue — saving your team from writing those uncomfortable follow-up emails.
White-label branding. Your clients should see your brand, not your billing tool's brand. The portal should support your logo, colors, and ideally a custom domain.
How to Set Up Your Agency Billing Portal
Setting up a client billing portal does not require months of development or a dedicated IT team. With the right platform, you can be operational within a day. Here is a practical, step-by-step approach.
The foundation of any billing portal is the payment processing behind it. You need to connect at least one payment provider that matches how your clients prefer to pay.
For European agencies, this typically means Stripe for card payments and international clients, Mollie for iDEAL, Bancontact, and other local European methods, and PayPal for clients who prefer PayPal's buyer protection. With PayRequest, connecting these providers takes minutes — enter your API keys, and the system handles the rest. PayRequest charges 0% on top of your provider's fees, so your only costs are the standard processing rates from Stripe, Mollie, or PayPal.
Agencies rarely have a single billing model. You probably have retainer clients on monthly subscriptions, project clients who pay per deliverable, and new clients who need to pay deposits before work starts.
Set up each model in your portal: create subscription plans for your standard retainer packages (for instance, a €2,000/month marketing retainer or a €500/month maintenance plan), configure deposit templates for project work (typically 25-50% of project value), and build invoice templates for one-off work.
Structuring these upfront means future billing is automatic rather than manual.
Migrate your existing clients into the portal with their contact details, billing preferences, and payment history. Most platforms support CSV import, making it straightforward to move from a spreadsheet-based system.
For each client, set their preferred currency and payment method, default payment terms (net-15, net-30), billing contact email, and any active retainers or recurring charges. Taking time to set this up properly means every future interaction is personalized and professional.
White-label the portal to match your agency brand. Upload your logo, set your brand colors, and configure email templates so every communication — from invoice delivery to payment confirmation — looks like it comes from your agency.
This branding consistency matters more than you might think. When clients receive a professional, branded invoice with a one-click payment button, they pay faster than when they receive a generic email with a PDF attachment. The portal becomes an extension of your client service, not a separate third-party tool.
The real power of a billing portal is automation. Configure these workflows to eliminate manual billing tasks.
For payment reminders, set up a sequence: a friendly reminder 3 days before the due date, a firmer notice on the due date, and escalating follow-ups at 7, 14, and 30 days overdue. Each email should include a direct link to the portal where the client can pay instantly.
For failed payment recovery (dunning), configure automatic retry attempts when a subscription payment fails. The system should retry at optimal intervals, notify the client about the issue, and alert your team only if automated recovery fails after multiple attempts.
For receipts and confirmations, enable automatic receipt delivery after every successful payment. Clients receive proof of payment immediately, and you never have to manually generate a receipt again.
Migrating Clients Without Disruption
The biggest concern agencies have about switching billing systems is disrupting existing client relationships. A thoughtful migration eliminates this risk.
Rather than switching all clients at once, migrate in waves. Start with new clients — every new engagement from today forward uses the portal. This lets you test the system with fresh relationships where there are no expectations to manage.
Next, migrate your most tech-savvy clients. These are the clients who already use self-service portals for their own business tools. They will appreciate the upgrade and provide useful feedback.
Finally, migrate long-term clients with a personal touch. Send a brief email explaining the new portal, emphasizing the benefits to them (24/7 invoice access, one-click payments, instant receipts), and offer a quick walkthrough if they want one.
Keep the announcement simple and benefit-focused. Something like: "We have launched a new client billing portal to make managing your account easier. You can now view all invoices, pay with one click, download receipts, and manage your subscription — all from one dashboard. Here is your personal login link."
Focus on what they gain, not on what you are changing internally. Clients care about convenience, not your operational efficiency.
If you have clients on active recurring billing through another system, coordinate the transition carefully. Set up the new subscription in your portal to start on the next billing cycle. Cancel the old subscription to end after the current period. Notify the client about the switch and confirm the billing amount remains the same.
This overlap approach ensures no payment is missed and no client is double-charged.
Measuring the Impact
A billing portal is an investment — even at €20/month, you should track whether it delivers value. Focus on these metrics in your first 90 days.
DSO measures the average number of days it takes to collect payment after invoicing. Before implementing a portal, most agencies see DSO of 30-45 days. With a well-configured portal and automated reminders, target DSO of 15-20 days.
Track this monthly. If DSO is not improving, examine which clients are dragging the average up and whether your reminder sequences need adjustment.
Track how many hours your team spends on billing-related tasks each week: creating invoices, sending reminders, answering payment questions, reconciling payments. Most agencies reduce this from 10-15 hours per week to 2-3 hours per week within the first month.
That recovered time is immediately available for client work, business development, or operational improvements that actually grow your agency.
Measure the percentage of invoices paid within terms. A good billing portal with automated reminders should achieve 85-90% on-time collection, compared to 50-60% with manual email-based billing. The remaining 10-15% typically requires one automated reminder before payment.
Pay attention to client feedback. Most clients appreciate the convenience of a self-service portal, but some may need a transition period. Monitor support requests related to billing — these should decrease significantly once clients are comfortable with the portal.
Common Mistakes to Avoid
After helping thousands of businesses set up billing portals, we have seen certain mistakes repeat. Avoiding them saves time and preserves client relationships.
Keep your billing structure simple. If you have 15 different pricing tiers with custom terms for each client, your portal will be harder to manage and your clients will be confused. Standardize where possible: 2-3 retainer packages, consistent payment terms, and clear project billing milestones.
Your clients' first interaction with the portal sets the tone. If the login process is confusing or the dashboard is overwhelming, they will revert to emailing you directly. Invest time in making the first experience clean, simple, and helpful.
Many agencies configure invoicing and subscriptions but skip the dunning (failed payment recovery) setup. This is a costly oversight. Without automated dunning, every failed payment requires manual intervention — exactly the work the portal should eliminate.
Agencies that do project work without collecting deposits expose themselves to scope creep and non-payment risk. Your billing portal makes deposits effortless — configure a standard deposit percentage (25-50%) and require it before project kickoff. Clients expect this from professional agencies.
Why PayRequest Works for Agencies
PayRequest was built specifically for businesses that bill clients regularly — making it a natural fit for agencies of all sizes.
The platform provides everything covered in this guide at €20/month: a branded self-service customer portal, automated invoicing and subscriptions, deposit and milestone billing, dunning and payment recovery, bank transfer support through Ponto (0% fees), integration with Stripe, PayPal, and Mollie, and automatic payment reconciliation.
Unlike accounting software repurposed for billing (QuickBooks, Xero) or developer-focused platforms (Stripe Billing), PayRequest is designed for the agency workflow: onboard a client, set up their billing, and let the system handle collections while you focus on delivering great work.
The self-service customer portal means your clients manage their own account details, payment methods, and invoice history — reducing your support burden while improving their experience.
Getting started takes less than 30 minutes. Connect your payment provider, import your clients, customize your portal branding, and send your first invoice. Your clients get a modern billing experience, and you get your evenings back.