Invoicing App for PR Agencies: Retainers, Project Fees and Hours Against Budget

A PR agency invoicing app bills monthly retainers and one-off project fees, passes through costs like wire distribution and media monitoring, and shows how many hours each retainer actually consumed. Describe how you bill and Mythex builds it on a real database.

Who it's for

Agency owners and finance leads who raise retainer invoices by copying last month's, forget to bill the wire fee, and suspect two clients are getting double the hours they pay for.

What you can build

Monthly retainer invoices raised on the same day each month
Project fees for launches, events, media training and crisis work
Pass-through costs billed at cost or with a set markup
Hours logged per client against the retainer budget
Invoices grouped by client entity for multi-brand groups
Overdue invoices listed by age

Retainer plus project, on one invoice or two

Most PR income is a fixed monthly retainer, with project work on top when a client launches something or has a bad week. Set each client's retainer amount and billing day once. Add project items as they are agreed, with a reference to the proposal. Some clients want one combined invoice; procurement teams often want separate ones. Ask for both options.

Retainer amount and billing day per client
Project items linked to the agreed proposal
Combined or separate invoices per client

Over-servicing shows up in the hours

A flat retainer hides how much work is going into it. Log hours per client, even roughly, and compare them with the hours the fee was built on. When a client has doubled their asks, you have the evidence to renegotiate scope rather than a feeling. Show the trend over three months, not one.

Pass-through costs that do not get forgotten

Wire distribution, monitoring tools, event venues, photographers and couriers are easy to pay and forget to bill. Record each cost against the client when it is incurred, choose at cost or with your markup, and it lands on the next invoice automatically.

Multi-brand clients

One parent company may have three brands, each with its own budget holder and purchase order. Model the entity that pays separately from the brand you work on, and print the right PO number on each invoice. It is the most common reason PR invoices are sent back unpaid.

A prompt to start from

Build an invoicing app for my PR agency. Each client has a monthly retainer with a billing day and an hour budget; staff log hours per client. Add project fees linked to a proposal, pass-through costs with an optional markup that roll onto the next invoice, and paying entities with their own PO numbers for multi-brand clients. Show retainer hours used vs budget over three months and overdue invoices by age.

Questions

Can retainer invoices be created automatically each month?

Yes. Ask for each client's retainer to generate an invoice on its billing day, ready for you to check and send.

Can clients pay online?

The app creates and tracks invoices. Card or bank payments need a payment provider account you connect yourself.

Can it work with my accountant's software?

You can export invoices and payments as a spreadsheet. Direct links to accounting software depend on what that software offers.

Do I need to code?

No. You describe how you bill and change it by chatting.

Is it free?

Free has daily credits and no card. Pro is $25/month.

Templates to start from

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Finance Dashboard Template — Board-ready finance reporting
Fintech Payments Site Template — Tiered pricing, blog, animations
AI Trip Planner Template — Chat itineraries with billing-ready UI
Invoice Generator Template — Canvas invoicing with PDF export
Expense Claims App Template — Receipt uploads with policy checks
Sales ROI Calculator Template — Three-scenario models and branded PDFs