Last reviewed: 8 August 2026
Quick summary
- You build custom GPTs, AI assistants or workflow templates for clients and need to decide whether the income is service work, digital products or both.
- Record client service fees and template sales separately, before AI tool costs and platform fees.
- The useful accountant conversation is about evidence: client scopes, GPT or assistant setup invoices, template marketplace reports.
Topic hub: Side hustle tax hub
Direct answer
A custom GPT or automation builder should keep four income streams separate: direct build/consulting fees, ongoing support or subscription fees, template or digital-product sales, and platform/marketplace payouts. Keep the client scope or product terms, invoice or payout export, refunds, platform fees and the actual bank settlement for each stream. An AI platform's terms can change, so do not assume a marketplace payment is the same type of supply as a direct UK client build.
VAT is a separate review point. The current UK registration threshold is GBP 90,000 taxable turnover. For digital services, the result can depend on whether the customer is a business or consumer, where they are located and whether a third-party platform accounts for VAT. Keep the customer and platform evidence so an accountant can review the actual model before a threshold is reached.
How money actually arrives in this niche
People in this niche rarely think in neat accounting words. They think in custom build fees, training sessions, maintenance retainers, template sales, support packages and referral commission. That is why a generic side-hustle calculator is not enough. You may see a payout, a dashboard, a retainer, a free product, a credit balance or a Stripe transfer and assume that is the tax number. It often is not.
The practical starting point is to list each income stream in the language of the platform or client. Then translate it into accounting records: gross income, refunds, platform fees, contractor costs, software costs and any non-cash value connected to work. This makes the page useful before an accountant call because the reader can send a clean summary rather than a folder of screenshots.
What figure should you record?
Record client service fees and template sales separately, before AI tool costs and platform fees. Keep the gross figure visible even if the platform pays out a smaller amount. If a client or platform deducts fees before money reaches your bank, the bank deposit may be a poor shortcut. If you receive products, credits, samples, usage rights or commission, keep those notes with the same discipline as cash receipts.
For the trading allowance, GOV.UK refers to gross trading income. That means you should understand the gross figure before deciding whether the trading allowance or actual expenses is more useful. If the activity grows, the same gross-income habit also helps with VAT and MTD checks.
Records to gather
For this exact niche, collect these before filing or speaking to an accountant:
- client scopes
- GPT or assistant setup invoices
- template marketplace reports
- AI tool invoices
- support retainer records
Add a one-line note explaining what each cost was for. A receipt called "subscription" is less useful than "ChatGPT Team for client chatbot builds, May 2026". That small habit is the difference between an accountant giving quick guidance and spending time reconstructing the story.
Real examples
- You charge GBP 350 to build a custom GPT for a recruiter. Keep the scope and invoice.
- You sell a reusable template for GBP 29. Track that separately from client consulting.
- A client pays monthly for updates. Record the retainer even if no major work is done that month.
Mistakes to avoid
- Mixing consulting and template sales with no category split.
- Not keeping client scopes for custom builds.
- Ignoring support retainers because they feel small.
- Claiming broad AI subscriptions without business-use notes.
The builder's four-lane money model
- Client implementation: discovery, prompt/workflow design, integrations, testing and handover, supported by a statement of work and invoice.
- Support retainers: monitoring, prompt iteration, user training and fixes, recorded by service month rather than confused with the build fee.
- Digital products: templates, prompt packs, automations or memberships, supported by checkout, refund and platform reports.
- Platform or referral income: revenue share, marketplace payout or affiliate commission, supported by current platform terms and the detailed report.
Record these lanes separately even if they land in one Stripe account. That makes recurring revenue, refunds, contractor payments and VAT review far clearer than a single annual category called "AI income".
Overseas customers and platform terms
Keep the client's legal name, country, business status and VAT number where supplied, alongside the agreement. For a direct overseas service, those details can matter to VAT place-of-supply analysis. For a marketplace sale, retain the platform's current seller terms, fee statement and any tax/VAT line shown. Do not borrow an answer from a direct-consulting client and apply it to an automated digital product sold through a platform.
Also keep cloud, API and software provider invoices separate from customer income. A USD API bill may raise conversion and, for VAT-registered businesses, overseas-services/reverse-charge questions. It is not a reason to net costs off a client invoice in the records.
Records to gather
- Statement of work, acceptance criteria, invoice and handover for each custom build.
- Retainer contract, support ticket/time summary, monthly invoice and payment trail.
- Marketplace or checkout export showing gross sale, refund, platform fee, payout and customer country where available.
- Customer business/VAT information and country evidence for direct cross-border work.
- Current platform terms for any marketplace or revenue-sharing programme.
- API, model, hosting, automation and subcontractor invoices, with a business-purpose note.
Real examples for this situation
- A GBP 1,500 chatbot build for a UK recruitment firm is recorded with the scope, invoice, acceptance and any continuing support fee.
- A GBP 29 Zapier template sold through a checkout needs its gross sale, refund and processor fee records, not just the net bank transfer.
- A US marketing client pays a GBP 400 monthly prompt-maintenance retainer: retain client-status/country evidence and the service-month invoice before assuming the VAT outcome.
- A platform revenue-share report is retained with its published terms and payout period, because monetisation eligibility and reporting can change.
Ask an accountant to review the point where the model moves from a handful of direct builds to mixed subscription, platform and international sales. That is when a generic freelancer bookkeeping approach starts losing the details that matter.
Questions to ask an accountant
- Is this service income, product income or both?
- Should templates and client builds be tracked separately?
- Can I claim AI tools and hosting?
- Do I need terms for client data and support?
- When would VAT or a limited company be worth discussing?
Send the questions with your totals. A useful accountant call starts with the money model, not just the job title.
Official guidance checked on 8 August 2026
Rules and thresholds can change. These sources were checked during this rewrite and should be rechecked before important filing decisions.
Related guides and tools
FAQs
What figure should I record?
client service fees and template sales separately, before AI tool costs and platform fees
What records should I keep?
client scopes, GPT or assistant setup invoices, template marketplace reports, AI tool invoices, support retainer records.
When should I speak to an accountant?
Speak to an accountant if the activity is regular, crosses a reporting threshold, involves VAT, MTD, gifted products, foreign currency, contractors, company structure or a tax return you are not confident filing.