How to connect ChatGPT to Mighty
ChatGPT is an AI assistant made by a company called OpenAI. When you connect it to Mighty, you can ask it questions about your company in plain words, and it reads the answer from your own figures. It can also prepare work for you to check, such as a draft invoice.
If you use Claude instead, read How to connect Claude to Mighty.
What you need first
- A ChatGPT account on a plan that lets you add your own connections. OpenAI changes which plans include this, so check your plan in ChatGPT if you can't see the option.
- Your Mighty email address and password.
- About 5 minutes.
If your ChatGPT account belongs to a Business or Enterprise workspace, the workspace's administrator may need to allow custom connections before you can add one.
How the connection works
You don't need a password or key from Mighty for ChatGPT. Instead, ChatGPT sends you to Mighty to sign in, the same way some websites let you sign in with Google. You then choose which company ChatGPT can reach and select Allow.
ChatGPT works as you. It can see the company you chose and nothing else. If you look after more than 1 company in Mighty, connect ChatGPT once for each company.
What ChatGPT can do in Mighty
| Area | What ChatGPT can do | Can it change your accounts? |
|---|---|---|
| Dashboard | Read your bank balance, profit, tax estimates, dividends available and unpaid invoices. It can also refresh those figures. | No. |
| Reports | Read your profit and loss report (your income and costs), your balance sheet (what the company owns and owes) and your trial balance (the balance on every account), for any period. | No. |
| Sales invoices | List and read your sales invoices (the bills you send customers so they pay you), and create a new one. | A new invoice is saved as a Draft unless you ask ChatGPT to raise it. A raised invoice counts in your accounts straight away. |
| Bank transactions | Look through the transactions waiting for you, read the receipts attached to them, and suggest what each one was for. | No. ChatGPT can only save a suggestion as a draft. You approve each one in Mighty. |
| Mileage | List your mileage claims (business journeys in your own vehicle that the company pays you back for), look up the distance between 2 places, and record a new claim. | Yes. Mighty has no draft mileage claim, so a claim ChatGPT records counts in your accounts straight away. To remove one, delete it on the Mileage Claims screen. |
ChatGPT cannot approve a bank transaction, delete anything, pay anyone or send anything to HMRC (the UK tax authority). ChatGPT may ask you to confirm before it changes anything in Mighty.
Things you can ask
- "What is my bank balance in Mighty?"
- "Which of my invoices are overdue, and how much do they add up to?"
- "Show me this year's profit and loss next to last year's."
- "Create a draft invoice to Acme Ltd for 3 days of consultancy at £600 a day."
- "Go through my bank transactions that still need sorting, read the receipts and save a draft for each one."
ChatGPT can make mistakes. Check a draft before you approve it, the same way you would check work from a new member of staff.
Turning the connection off
To stop ChatGPT reaching your company, go to Company Settings, open the Other tab and select API Keys. Under Connected apps, select Revoke next to ChatGPT, then confirm.
ChatGPT loses access straight away. To use it again, connect it again from ChatGPT.
You can also remove Mighty in ChatGPT, on the Plugins page. Removing it there does not turn the connection off in Mighty, so revoke it in Mighty as well.
Common questions
What if I can't see Plugins or Add custom MCP server?
OpenAI is changing where this option lives. On some accounts it is under Settings, then Apps & Connectors, then Advanced, where you switch on Developer mode first and then create the connection. If you can't find it in either place, your ChatGPT plan may not include it, or your workspace administrator may have turned it off.
What if ChatGPT says it cannot connect?
Check that the address is exactly https://api.mightyaccounting.com/mcp, then try
again. If the Mighty sign-in page says the sign-in expired, start again from ChatGPT: the link it
opens can only be used once, and only for a few minutes.
Why can't I see my company when I sign in?
Mighty only lists the companies you can connect. If you only have access to some areas of a company, you can't connect an assistant to it, because ChatGPT would see the whole company. Ask the company's owner or your accountant to connect it instead.
Can someone else see that ChatGPT is connected?
Yes. Everyone who can open API Keys for the company sees the connection under Connected apps, with who connected it and when it was last used. Any of them can revoke it.
How do I know what ChatGPT has done?
Draft invoices are in your invoice list, and draft bank suggestions are on the bank transaction, ready for you to approve or change. Mileage claims ChatGPT records are on the Mileage Claims screen.
