Relación con inversionistas

Providers Frequently Asked Questions

Find out the questions frequently asked by suppliers at the beginning of the pre-contractual, contractual, and post-contractual stages of the contracting process. To display the FAQ menu, click on +

Providers FAQ

What is the periodicity for generating the tax certificates?

  • Income tax withholding: Annual
  • Sales tax withholding: Bimonthly
  • Industry and Commerce tax withholding: According to the periodicity for submitting the Industry and Commerce tax return for each municipality, for example:
    District of Bogotá: Bimonthly
    Municipality of Medellín: Annual
    Municipality of Santiago de Cali: Annual
    Municipality of Barranquilla: Monthly
    Municipality of San Carlos: Annual
    Municipality of Sabaneta: Annual
    Municipality of Sabanalarga: Annual
    Municipality of Soledad: Monthly

If I have a question about the information generated, who can I talk to?

If the password is blocked, who can I talk to?

What is the date of publication of the certificates?

  • Income tax withholding: Before March 15 of the following year
  • Sales tax withholding: Within 15 calendar days after the two-month period of withholding
  • Industry and Commerce tax withholding: Within 10 calendar days of withholding

What is the procedure to follow in the event of over-withheld tax or improper withholdings?

For tax withheld at source as income, sales tax and industry and commerce tax, provisions of Article 6 of Regulatory Decree 1189 of 1998 must be followed, as follows:

What industry and commerce withholding rate will be applied to my payments?

The rates are applied as established in the Tax Statute of the Municipality where the service is provided or the respective purchase is made, taking into account the code of the supplier's activity.

Which municipality applies the industry and commerce withholding?

  • For services, in the municipality where the service was provided.
  • For goods, in the municipality where the supplier is located.

What contracting regime is applicable for ISA?

In accordance with provisions of Article 32 of Law 142 of 1994, paragraph of Article 8, in line with Article 76 of Law 143 of 1994, the legal regime applicable to actions and contracts of the Company is the private law regime. For contracting processes, standards provided in the Regulation for contracting goods and services in accordance with the Business Policies would be applied. For aspects not covered, provisions of the Civil Code, the Commerce Code, or the rules applicable would be applied.

What is the Closing Date of a Purchase Process?

At the end of the period for submission of biddings for analysis and evaluation.

What is the procedure for registering as a supplier of ISA?

Registro de Proveedores

What are the energy transport business categories that ISA manages centrally for the company group?


What are the criteria for selecting the contractor?

Compliance with legal, technical and commercial requirements as required in each process and as stated in Agreement 108: Regulation for Acquisition of Goods and Services

What is ISA's availability for receiving physical documents at its Medellín headquarters?

Monday to Friday from 7:30 A.M. to 6:00 P.M., Document Management - document reception area. Out of these hours, as well as on Saturdays, Sundays and holidays, documentation is received at any time, but at the main gate. This availability applies for the whole year.

How can I send my goods and services offers to ISA via e-mail?

For you to be considered in a contracting process, you must be registered in our ISA supplier registration platform, which contains the information of the goods and services that you offer and that we need. To find out about the supplier registration process, please go to the SUPPLIER’S REGISTRATION section.

How can I receive additional information on the payments that I can consult through the “Customized Information” section?

Should you require additional information related only to payments, please call the number (4) 317 20 42 of Medellín from Monday to Friday from 2:00 p.m. to 4:30 p.m., or send an email to

​Cautionary note

Certain statements included in this report are “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995.

These forward-looking statements reflect our current perspective regarding future events, are based on presumptions, and are subject to risks and uncertainties. In addition, these forward-looking statements present our estimates and assumptions only as of the date of this report. With the exception of our ongoing obligation of disclosing important information, as required by federal securities laws, we are not intending to update them in relation to any future review of the forward-looking statements in order to reflect events or circumstances occurring after the date of this report.

Amounts are expressed in USD only for information purposes, and do not reflect accounting conversion techniques usually applicable.

Quarterly figures are not audited and are expressed in millions of Colombian pesos (COP). The consolidation process implies the inclusion of 100% of the companies where ISA has control, according to the application of the International Financial Reporting Standards – IFRS – applied in Colombia as of January 1, 2015.