Since 2020 every public tender in Bulgaria has been run through the Centralised Automated Information System for e-procurement – CAIS EOP. Notices, documents, questions, bids, opening and decisions all go through the platform. You cannot take part without registering in it.
Registering the company
Registration is free. You need:
- a qualified electronic signature (QES) of the person who will represent the company in the system;
- the company's details – company number, address, representative;
- a work email where you will receive the system's messages.
After registration the representative can add staff with different rights: some prepare the bid, others sign and submit it. Do this from the start – submission should not depend on one person and one signature.
What to watch on the platform
Every procedure you take part in has a messages section. Through it the buyer sends clarifications, invitations to the opening, requests for additional documents and the decisions. A missed message means a missed deadline. Turn on the email notifications and check the section every working day while the procedure is running.
Submitting the bid
The bid is filled in and uploaded in a structured form: separate fields and files for the participation documents, the technical proposal and the price proposal. The price proposal stays sealed until the committee opens it.
A few practical rules:
- Start uploading at least one working day before the deadline.
- Sign every document that needs a signature with the QES of an authorised person. A signature of an employee without the rights counts as a missing signature.
- Check the limits on file format and size in the documents.
- After submitting, download and keep the confirmation with the date and time.
The most common technical problems
- An expired or changed QES. Check its validity a week before the deadline.
- Browser and settings. The platform works with particular browsers and signing components; test on the computer you will submit from.
- Files with unusual names. Use short names in Latin letters without special characters.
- Last day, last hour. The system closes exactly at the announced time. A server delay is no ground for an extension.
What cannot be fixed after the deadline
Once submitted, a bid can be withdrawn and submitted again only until the deadline. After it, neither new documents nor corrections on your initiative are accepted. The committee may ask for clarification or completion only in the cases the law allows, and only for the compliance documents – not for the price or the technical proposal.
Updated on 1 Oct 2026. The article is general information, not legal advice.
