The evolution of William AI: Bringing frontier AI to every Apron user (and how we’ll price it)

AI is fundamentally transforming bookkeeping. Since launching William AI earlier this year, our goal has been clear: create an autonomous bookkeeping agent that handles the heavy lifting across your payments and accounting workflows.

Instead of acting as a passive add-on, William AI has quickly embedded itself into almost every step of the process. From retrieving missing receipts directly from client inboxes to categorising documents and publishing them straight to your ledger, William acts as a true digital team member.

One of the biggest breakthroughs for our accounting and bookkeeping partners was the ability to train William using plain, conversational English. Rather than configuring rigid code or complex logic trees, you could instruct William just like a human employee —setting policy rules for specific suppliers, tax rates, and thresholds. This approach freed up firm capacity without increasing overheads.

Today, we are excited to introduce Guidance 2.0, the next major step in William AI's evolution.

Alongside these upgrades, we are making a fundamental structural change: William AI is moving out of its tier-restricted availability and becoming embedded directly into Apron’s core Capture product. 

It will no longer be limited to Silver-tier Apron Books Club partners and above. Frontier AI bookkeeping will now be accessible to every single user on the Apron platform.

Here is a look at what’s new with William AI, why we are shifting our platform approach, and how our pricing structure is evolving to support it.

What’s new with William AI (Guidance 2.0)

Guidance 2.0 makes William AI more intuitive, granular, and proactive. You can now guide William on virtually any task using natural language, while William takes an active role in learning your firm’s unique workflows.

1. Completely free-form guidance

You can now write guidance about anything in plain English: referencing suppliers, ledger categories, VAT rates, or tracking categories.

• Custom Categorisation & VAT: Explain nuanced rules just as you would to an assistant. For example, "Invoices from Vodafone are always Telephone and Internet, with 20% VAT and tracking category – Administration"

• Detailed Descriptions: Instruct William on how to handle line context: "Use the reference from the "Purchase Order Number" section on the purchase invoice as the description.", or “The invoices from BOOKER need splitting between 3 main categories: COGS Food, COGS Drink, and Consumables”

• Auto-Publish Rules: Set strict safety boundaries on what William can publish autonomously. Tell William "Never publish documents over £1,000 automatically" or "Only auto-publish fuel receipts."

2. Proactive guidance suggestions in your inbox

Instead of waiting for you to write rules from scratch, William now actively analyses your manual corrections, spots repeating patterns, and suggests ready-made guidance right inside your Inbox. You can save a suggested rule in a single click or answer a quick prompt so William understands your intent better

3. Complete context with referenced documents

Trust requires transparency. Every guidance suggestion provided by William includes the underlying source documents and historical corrections that inspired it. You can see exactly what William originally picked and what you changed before deciding to approve the rule.

4. Automated tracking category prediction

If your practice uses tracking categories (like region, project, department, or site), William learns how you apply them over time and automatically pre-fills them. Want more precise control? Simply add a line of guidance, such as "Set the project based on the site address on the invoice."

5. Line-item precision

Bookkeeping rarely fits into neat single-line summaries. William can now extract, categorise, and apply VAT or tracking categories to individual line items. It also follows complex line-grouping instructions, such as "Split supermarket invoices into separate lines for food, drinks, and cleaning, each with its own category and VAT rate."

Embedding William AI into core Capture: Why pricing is changing

When we launched Capture in 2024, AI was largely treated as an added extra. Fast forward to today: AI is no longer a peripheral feature. It sits at the core of data capture, workflow execution, and decision-making across the payments lifecycle.

We believe our partners shouldn't have to choose between basic OCR software and frontier technology. By integrating William AI directly into our core Capture offering, we ensure that every accountant, bookkeeper, and business on Apron has immediate access to the best technology available.

To support this continuous investment in AI capabilities and infrastructure, we are updating our pricing structure, starting from the 1st of December, 2026.

How the updated pricing structure works

• Preserving the Base Fee: We are keeping our core £5 / client entry tier for standard clients.

• Tiered Plans for Larger Clients: To better reflect the higher volume, complexity, and value delivered to larger client accounts, we are introducing £11 and £21 plans.

• Enhanced Client Workflow Tools: Higher tier plans now include advanced workflow tools designed to solve one of bookkeeping’s biggest headaches: chasing down missing client documents.

You can learn more about the new pricing structure here.

Protecting pricing for our existing Partners

Our existing partners have been instrumental in helping us build and refine both William AI and Apron. To honour our original commitment we're keeping the £199 cap for existing Gold or Platinum partners who are on the cap by the 1st of December, 2026. Eligible practices will have all existing clients automatically upgraded to our highest plan at no extra cost. New clients added after the 1st of December will be billed on top of the cap.

Gold status can be reached with 50 active clients, or with as few as 7 clients with deep platform adoption. This ensures that our current partners can continue scaling their practices without experiencing significant price increases. 

To ensure a smooth transition, our team will be reaching out with more details on your specific situation by the 15th September and guide you through the process. You can also book some time directly with us here.

Looking ahead: Built for the whole life of a payment

From capturing receipts to running payroll, paying bills, and earning rewards on business spending, Apron is built to manage the entire lifecycle of a payment.

Integrating frontier AI into document capture is just one milestone in our broader mission. We remain committed to innovating across AI bookkeeping and payments, building intelligent, transparent, and flexible tools that save your firm time and keep your clients growing.

Looking for what else is new to Apron in September? Check out this month's product release blog to learn more about Apron’s new merchant cards, improvements to the missing document workflow as well as the arrival of mobile payments with the Apron app.