Accounting firm or other agent: how to request authorisation to take care of someone else’s taxes

Your accounting firm needs an authorisation mandate for handling its clients’ taxes. You can log in to to send a request to the natural person, company or other corporate entity electronically.

Note: it is necessary for the person, company, etc. to answer your request and accept it, i.e. your client must give you the authorisation mandate. The way they do so depends on whether the client uses their personal e-bank codes or a mobile certificate or certificate card.

How to authorise employees of your accounting firm — how to send an online request to your client


Give authorisations inside your accounting firm

If you are the Managing Director, manager, or another holder of the right to sign for the accounting firm, you can give an authorisation mandate via to anyone of your employees as follows:

  1. a representative’s right to grant a mandate. This means that your employee (who works as an accountant) can send out requests for acceptance of an authorisation as described in the instructions on this page.
  2. a specific mandate for representation, which makes it possible for your employee to handle the client’s affairs as the client has instructed the accounting firm when giving it the authorisation.

If you prefer, you can give the mandate to your employee later. When you give the mandate to represent, do not forget to select the appropriate themes (like “Managing tax affairs”) – in other words, the themes the accountant deals with on the client's behalf.

In addition, accounting firms can restrict their employees’ mandates: you can use a mandate specifier to limit or target a mandate to apply only to a certain property, a client company or its department. The MyTax view on each employee’s workstation lists the clients accordingly. For more information, see Grant an authorisation as a company or organisation — “How do I use a mandate specifier?”.

Go to e-Authorizations

Examples of company mandates on


Find out the authorisations you need

“Managing tax affairs” allows you take care of all the client’s tax matters. The other authorisation mandates allow you to take care of only some specified matters.

Read the descriptions of different authorisations to decide which authorisation you need

You can select the authorisation later on


Request an authorisation on

Log in to the e-authorisation service with your personal e-bank codes, a mobile certificate or a certificate card. After that, you can submit an authorisation request to take care of your client’s matters.

Go to e-Authorizations

Instructions on Request a mandate as a company or an organisation


Ask the client to accept your authorisation request

  1. If the client has personal e-bank codes, a mobile or card certificate, ask the client to log in to and accept your request.

    Note: if your client is a company or organisation, the people who have the right to sign for the company are listed in the company’s Articles of Association. These people are the ones who can accept your request. e-Authorizations

    Instructions on Approving a mandate request

  2. If your client does not have any e-bank codes, mobile certificates, etc., ask the client to go to a tax office and take a passport, photo ID card, driving licence or some other identification with a photo with them. Your client must be identifiable from the photo. Your client can accept the authorisation request at the tax office, but they must go there in person.

    If one person goes to the tax office on all shareholders’, co-owners’, etc. behalf, he or she must also have:
    • a power of attorney showing that he or she has the right to sign on all the shareholders’ behalf (the power of attorney cannot be more than 6 months old)
    • photocopies of the passports or photo ID cards of all the shareholders who signed the power of attorney and who are not present at the tax office
    • if the authorisation concerns an estate of a deceased person and the estate has a Business ID, a photocopy of the list of parties to the estate.

Addresses and opening hours of tax offices


You can manage the client's taxes online

When your request is accepted, Authorizations will show your mandate.
You are able to log in to the Tax Administration’s e-services with your personal e-bank codes, a mobile certificate or a certificate card.

After logging in to MyTax, select “Act on behalf of a company” or “Act on behalf of someone else”, depending on whether you are taking care of a company’s or an individual client’s taxes.

On the accounting firm employee’s workstation, MyTax will now show all the names of the firm’s clients that this employee is authorised to handle taxes for.

Frequently asked questions

You can cancel any authorisation mandates in that have previously been granted on behalf of a company or corporate entity behalf if you have

  • The right to grant authorisations on the company’s/entity’s behalf
  • The right to sign for the company/entity, with an official registration of this right – in the Trade Register or elsewhere – based on holding one of the positions:
    • The company’s Managing Director
    • Self-employed individual who operates trade or business
    • Party authorised to sign for the company (alone, with no other person as a co-signatory)
    • Holder of the right to sign for the company because one of the parties listed above has granted that right via to the holder
    • An authorised signatory in a registered association (signing for the association alone, with no co-signatory)

Instructions for invalidating mandates

  1. Log in to
  2. Select the “assignor” i.e. the company/corporate entity that had issued the mandates you want to cancel.
  3. First select Granted mandates, and then select Invalidate selected mandates as appropriate.

If you cannot log in to the e-service of “ Authorizations”, complete the Application for the invalidation of a mandate, also available on the website. Submit the completed form to cancel the authorisation mandates.

If the guardian has not previously used the Katso ID, he or she cannot act on the person’s behalf in MyTax or other e-services of the Tax Administration.

If you are a guardian who has previously used the Katso ID, submit an Application for the registration of a mandate to get a authorisation.

Fill in the application form and refer to your existing Katso User ID.

Read more about when you can/cannot act on someone else's behalf on

If you use a strong personal identifier to log in, your authorisation is no longer checked in the list of Katso service authorisations. You need a authorisation to replace the Katso authorisation.

When you identify yourself to the service with your online banking codes, a mobile certificate or a certificate card, your authorisation to handle matters on behalf of the organisation will be checked with the

  • Trade Register
  • Business Information System (BIS)
  • Register of Associations
  • Authorisations service.