Tax review across all your clients
Which tax returns each company files, based on the taxes set up in Holded, and what is missing before filing: unissued invoices, unrecorded purchases, unreconciled bank.
Talk to your Holded in human — or in Spanish, Russian, Chinese, Portuguese, Romanian or Ukrainian
Ask in your own language in ChatGPT or Claude; the answer comes from your Holded data.
You only pay per company, and accounting-firm mode (modo asesoría) is included. Work out your Multiempresa price →
Works with
Claude
ChatGPT
Holded
ClaudeChatGPTHoldedBy 
Verifactu Business, Holded Solution Partner
Nova GestiónQ4 VAT · to review
Talleres RiberaQ4 VAT · to review
Norte DiseñoQ4 VAT · up to date
Lúa CaféQ4 VAT · up to date
Holdedisaak.proChatGPT · ClaudeYour assistant · ChatGPT or ClaudeAMJLRC
isaak.pro connected
Which clients still have Q4 VAT to review?
AM✓ Checked in Holded · 4 companies
CompanyQ4 VAT
Nova Gestión4 invoices to review
Talleres Ribera1 expense without VAT
Norte DiseñoReviewed
Lúa CaféReviewed
Two clients pending. Shall I write to ask for what is missing?
Your assistant
And the Talleres Ribera expense?
JL€182.40 invoice from 14/10, VAT not itemised.
The help centre, the legal documents and the dashboard are in Spanish for now. The WhatsApp assistant replies in English, and email support is in English too.
What you can ask it
Ask in your own words, in your own language. Isaak checks Holded for you and, whenever something changes data or goes out to a client, shows it to you first and waits for your confirmation.
Sales and collections
Invoices (facturas), credit notes, quotes, pro formas and receipts. What is overdue, what has not been issued and who pays late.
Reminders and email sending
Send each client their invoice or a payment reminder from the company's own Holded, with wording you approve.
Purchases and documents
Expenses, expense accounts and the Holded inbox (bandeja de entrada) to review or record them.
Bank and treasury
Bank and cash transactions, unreconciled items, payments, remittances and collection forecasts. It records the payments you confirm; it never makes payments or transfers.
Accounting
Chart of accounts, the full journal (libro diario) over long periods, entries and the taxes you have set up.
Customers and suppliers
Find contacts, their records and attachments. Create or update a contact once you confirm.
Drafts with your approval
Prepares draft invoices and balanced journal entries in Holded. Isaak proposes and you confirm every change: it deletes nothing and makes no transfers.
Teamwork in the same company
Invite your team or your accountant (asesoría), or request access to a company that is already connected. The owner (titular) decides each person’s role and can remove it at any time.
Summaries for your client
A summary of sales, expenses, collections and cash for one company or for all your clients, ready to send or present.
Why isaak.pro
No missed deadlinesReview every company before each deadline and see what is missing for each tax return.
One chat for every companyNo separate connection or conversation per company: ask by name or tax ID (CIF), and every figure says which company it belongs to.
Email sending from HoldedInvoices and reminders to each company's clients, from that company's own Holded and with your wording.
Several people in the same company, as in HoldedYour team, your accountant (asesoría) and your client work on the same company at the same time, each with their own user and role (read-only or full access). If someone has already connected it, request it from the dashboard and the owner (titular) approves it: no duplicate copies.
Alerts that save you headachesAn email whenever a new assistant connects, and a warning in the chat before you run out of Holded API calls.
Claude and ChatGPT without paying twiceUse either assistant; a company counts once even if it is connected to both.
Grows with youStart with one free company and, when you have more, carry on with the same connector and the same chat.
Built by an accounting firmIt is developed and used every day by an accounting firm that is a Holded Solution Partner.
Which plan is right for you?
Free
1 company, foreverYou have one company in Holded and want to use it from Claude or ChatGPT.
- Connected by the owner or an administrator of its Holded.
- If you add more companies tomorrow, you keep the same connector.
Multiempresa
From the 2nd company, in tiersYou own or run several companies: an SL and a self-employed business (autónomo), or several companies.
- All your companies in one chat.
- Each company connects with the key from its own Holded.
Accounting-firm mode
Same price as MultiempresaYou manage third-party companies: accounting firms (asesorías, gestorías), representatives and external managers.
- Your team, with permissions per company.
- Data processing agreement (encargo de tratamiento).
- A guide to request the key from each client.
Secure by design
The assistant never sees your Holded keys, and nothing is written without your confirmation.
More about security (in Spanish) →- Only the right person can connectIn Holded, only the account owner or an administrator can create an API key. Before authorising, you see the company name and tax ID (CIF).
- Each company has its own keyA company never shows another company’s data, even in the same chat.
- Nothing gets deletedIsaak proposes and you confirm every change: it deletes nothing and makes no transfers.
- Keys are encryptedThey are stored encrypted and never passed to Claude or ChatGPT: the assistant gets its own access, which you can revoke.
- We don't store your Holded dataThe connector only asks Holded for what it needs to answer, and stores neither questions nor answers.
- Control and transparencyAn email for every new authorisation, and a dashboard with your companies, connections and access.
Free with one company. Multiempresa when you grow.
You only pay per connected company, not per user or per assistant. Move the slider to see what you would pay.
Free · 1 company, foreverMultiempresa · from the 2nd company, in tiersAccounting-firm mode · included, at no extra cost
1 free + 9 × €1.50 + 2 × €1.00 = €15.50 a month, excluding VAT (IVA).
How it is calculated: the 1st company is free; after that, per company per month, companies 2–10: €1.50; 11–50: €1.00; 51–100: €0.75; from 101: €0.50. Monthly, no minimum term; Holded and your Claude or ChatGPT plan are paid separately. Every company connected in a month is charged for the whole month, with no pro-rating, and before adding it we show you its price and your next invoice for you to confirm. Nothing is charged until you turn on Multiempresa yourself in “Plan y facturación” and accept the amount; any price change is announced 30 days in advance. Pricing policy (Política de precios)
Accounting-firm mode: for people who manage other people's companies
Accounting firms (asesorías, gestorías), representatives, directors and external managers. Same price as Multiempresa, plus what you need to work with third-party data.
- Your team, with permissions per company: read-only or full access.
- Data processing agreement (Encargo de tratamiento) for your clients' data.
- A guide and a ready-made message to ask each client for their Holded key.
How does your accounting firm work with each company in Holded?
The connector uses each company's API key. Whether it can be connected depends on how the company is set up in Holded.
Can be connectedCollaborative (colaborativa)The company has its own Holded plan and creates its own key.
Being checkedMixed (mixta)The company pays for the base plan and the accounting firm for the accounting licence. We are checking with Holded what the API allows.
Not yetManaged (gestionada)The accounting firm runs the company and the company never logs in to Holded: Holded does not allow a key to be created.
Connect your first company in three steps
Copy the connector address and add it in Claude or ChatGPT. Isaak will ask for your Holded key when you authorise. The Holded and Isaak screens are in Spanish, so the button names are given below.
https://isaak.pro/mcpDon't have Holded yet? The connector needs a paid Holded plan. Request a trial and we will help you in English →
1 · In Holded
Create the company's key
Configuración → Desarrolladores → Credenciales → “+ Agregar API Token”, with “Por áreas” permissions. Copy the key (it starts with pat_).
2 · In Claude
Add the connector
Customise → Connectors → “Add custom connector”. Paste the address and click “Add”. Requires Claude Pro, Max, Team or Enterprise; in Team and Enterprise an owner adds it.
Open Claude →2 · In ChatGPT (web)
Add the MCP server
Apps → “+” → “Add custom MCP server”. Give it a name, paste the address into the connection field, choose OAuth authentication and create the app.
OpenAI guide →3 · Authorise
Isaak opens: sign in with your email, paste the key and check the company name and tax ID (CIF) before authorising. To add more companies, use “Conectar otra empresa” and, at the end, “Autorizar con todas mis empresas”.
Don't have Holded yet? Request a trial
Tell us about your company and we will help you choose a Holded plan, sign up (alta en Holded) and connect it to ChatGPT or Claude. In English.
Everything in plain sight
What we offer, what it costs, how to start and whom to ask. Everything about Holded itself is on its official pages.
Get started
Your first company is free forever, with every feature.
Help and guides
Step by step: key permissions, accounting firms and error messages. In Spanish for now.
Talk to us
The WhatsApp assistant replies in English; email support in English, during office hours (Mon–Fri, 9:00–18:00 Madrid time). Support for the connector is ours.
Holded itself
For questions about Holded: plans, features and training.
Terms and data
What you sign up for, what it costs and what we do with your data. The documents are in Spanish.
Frequently asked questions
How much does it cost?
Your first company is free forever. Extra companies are priced in cumulative tiers, per company per month, excluding VAT (IVA): companies 2–10: €1.50; 11–50: €1.00; 51–100: €0.75; from 101: €0.50. For example: 10 companies, €13.50; 25 companies, €28.50; 100 companies, €91.00 a month. Nothing is charged until you turn on the Multiempresa plan yourself in “Plan y facturación” and accept the amount; any price change is announced 30 days in advance.
How is a company connected mid-month charged?
Every company connected during a month is charged for the whole month, even if it was connected for an hour: no pro-rating and no refunds. If you archive or disconnect it, it stops being charged from the following month, and reconnecting it in the same month is not charged twice. Before adding each company we show you its price and your next invoice, and it is only added once you accept.
How can I try it before paying?
Connect your first company: it is free forever and has every feature. If you don't use Holded yet, request a Holded trial and we will help you sign up (alta en Holded) in English.
What is the difference between Multiempresa and accounting-firm mode?
The price is the same. Multiempresa is for people connecting their own companies. Accounting-firm mode (modo asesoría) adds what you need to work with other people's companies: your team with permissions per company, the data processing agreement (encargo de tratamiento) and a guide to request the keys. If you are a representative or external manager of other people's companies, this is the one for you.
Who can connect a company?
Its owner or an administrator in Holded: they are the only ones who can create the API key. Whoever connects it must be a director or representative of the company, or have its permission. If you manage third-party companies, the data processing agreement (encargo de tratamiento) governs how their data is used.
What can Claude or ChatGPT do with my data?
Only what the key you created in Holded allows: with “Leer” (read), it can only view (invoices, purchases, bank, accounting, contacts); with “Full”, it can also create draft invoices, contacts or journal entries and record payments you confirm; it never makes payments or transfers. It asks for confirmation before every action. It deletes nothing and does not file taxes. You can revoke access from the dashboard or by deleting the key in Holded.
Do I pay per user or per assistant?
No. Only per connected company. Your team and your assistants do not count, and a company connected to both Claude and ChatGPT is charged once.
Is there a minimum term?
No. It is monthly and you can disconnect companies whenever you like; the free company always stays. Holded and your Claude or ChatGPT plan are paid separately. From the dashboard you can download your data or close your account at any time.
Do I need a Holded account for each company?
Yes. Each company connects with a key created in its own Holded (the API is only available on paid plans). Companies run by an accounting firm without their own Holded licence cannot create that key yet. If you don't have Holded yet, request a trial and we will help you sign up.
I have an SL and I'm also self-employed (autónomo). Do I pay for two companies?
If they are two Holded accounts, yes: the first is free and the second costs €1.50 a month, excluding VAT (IVA).
Does my accounting firm's key give access to my clients?
No. It only opens your firm's data. Each client needs the key from their own Holded; the guide for accounting firms includes a ready-made message to request it.
Do you store my Holded data?
No. The connector only asks Holded for what it needs to answer, and stores neither questions nor answers. We store the encrypted key and a technical usage log (date, tool, company and result) for security and support. The database is in the European Union (Frankfurt).
Is Isaak part of Holded?
No. isaak.pro is an independent service from Verifactu Business, a Holded Solution Partner. The company details are in the legal notice (Aviso legal). It uses the public Holded API with a key you create. Support for the connector is ours; support for Holded is Holded’s.
Which Claude and ChatGPT plans work?
In Claude, the Pro, Max, Team and Enterprise plans (in Team and Enterprise, an owner adds the connector). In ChatGPT, the web version; in Business, admins create it, and in Pro it is read-only.
Does it file my taxes?
No. It works with the Holded data you have given it access to. It does not file tax returns or replace professional advice. To learn bookkeeping in Holded, there is the official Holded Academy training.
Something isn't working. How do I contact you?
Message us on WhatsApp (the assistant replies in English) or email soporte@isaak.es (email support in English). The guide to common errors is in Spanish for now. For questions about Holded itself (plans, Holded invoices, product features), use its help centre.