Privacy policy
SrpskiEffective from 7 October 2026 · version 2026-10-07
This is a translation. If the two versions differ, the Serbian version prevails.
This policy explains which personal data we process when you use the Calculus IOS service at ios.calculus.rs (exchange of statements of open items – IOS – between users of the Calculus ERP and their business partners), for what purposes, how long we keep it and what your rights are. Processing complies with the Serbian Law on Personal Data Protection (“Official Gazette of RS”, no. 87/2018; the “Law”).
1. Controller and contact
Calculus d.o.o. Beograd, Studentski trg 19/III, 11000 Belgrade (Stari Grad), Serbia
Tax ID (PIB) 103314980 · Company reg. no. (MB) 17543270
Email: podrska@calculus.rs
For any question about data processing or to exercise your rights, write to podrska@calculus.rs.
2. Whose data we process
- Customers – companies that open an account and send IOS documents from their ERP (the “customer”).
- Recipients – the customer's business partners (debtors) who view and answer an IOS through a link.
- Persons named in an IOS – e.g. sole traders or contact persons whose name, address or phone number appears in the creditor or debtor data.
3. What we process, why and for how long
| Data | Purpose | Legal basis | Retention |
|---|---|---|---|
| Customer account: email address, company name, password (only as a one-way cryptographic hash), role, email verification status, registration and last sign-in time, failed sign-in count and lockout, version and time of accepting the Terms of use | Opening and running the account, sign-in, account protection | Performance of a contract (Art. 12(1)(2) of the Law); legitimate interest in security (Art. 12(1)(6)) | While the account exists. Deleted within 30 days of a request, except data we must keep by law. Unverified registrations are deleted automatically after 30 days. |
| Codes and links for email verification and password reset (stored only as hashes) | Verifying the email address, changing the password | Performance of a contract | Valid for 30 minutes; deleted or invalidated after use. |
| Customer API key (stored only as a hash) | Receiving documents from the customer's ERP | Performance of a contract | While the account exists. |
| IOS documents: the PDF, creditor and debtor data (name, address, tax ID, registration number, code, phone), line items (order numbers, descriptions, dates, amounts), the recipient's answer (accepted and disputed items, note, time) and the PDF the recipient attaches | Delivering the IOS to the recipient, receiving the answer and showing it to the customer | Processed on behalf of the customer (the customer is the controller, we are the processor – Art. 45 of the Law), under the Terms of use | 30 days from upload. When the link expires, the document, all IOS data, the answer and the attached PDF are permanently deleted (automatically, once a day). |
| Emails we send (address verification, password reset, notice that a recipient answered) | Operating the account and the service | Performance of a contract | Not stored in our database; a copy stays in the sending mailbox under that service's rules. |
| Technical access data: IP address, time, requested page address, server response, browser type | Security, abuse prevention, troubleshooting | Legitimate interest (Art. 12(1)(6) of the Law) | 30 days (web server access log). For rate limiting, IP addresses are held only in memory, for at most 1 hour. |
| Application log: internal account and document identifiers, sign-in outcome, errors (no passwords, codes or document contents) | Security and operation of the system | Legitimate interest | Size-limited circular log; older entries are overwritten automatically. |
| “I am not a robot” check (Cloudflare Turnstile): IP address and technical characteristics of the browser and device | Protecting forms from automated attacks (always when answering an IOS; on sign-in and registration only when activity looks suspicious) | Legitimate interest in security | We keep only the result while handling the request; Cloudflare processes the data under its own privacy policy. |
We do not carry out automated decision-making or profiling within the meaning of Art. 38 of the Law. The “I am not a robot” check and rate limiting serve only to protect the service. We do not sell data or use it for advertising.
4. Cookies and local storage
We use only what is strictly necessary for the service to work, so we do not ask for separate cookie consent (providing a service you explicitly requested). We use no analytics or advertising cookies.
| Name | Purpose | Duration |
|---|---|---|
__Host-IOSdocs.Session | Signing in to the account (encrypted, readable only by the server over HTTPS) | Until the browser is closed and at most 10 hours; with “Remember me” 7 days from sign-in. Signing out deletes it. |
__Host-IOSdocs.Antiforgery | Protects forms against forged requests (CSRF) | Until the browser is closed |
iosdocs-theme (browser local storage) | Remembers the light or dark theme you chose; never sent to the server | Until you clear it |
| Cloudflare Turnstile | Security check on the sign-in, registration and IOS answer pages; Cloudflare may temporarily use technical data in the browser solely for this check | During the check |
5. Who may receive the data
- The IOS recipient – the IOS data intended for them, through the link the customer sends.
- The customer – the recipient's answer (decisions per item, note, attached PDF).
- Processors providing services to us: Microsoft (Microsoft 365 – sending email) and Cloudflare, Inc. (Turnstile – “I am not a robot” check). The service and its data are on a server operated by Calculus d.o.o..
- Public authorities – only where required by law.
Microsoft and Cloudflare may process data outside the Republic of Serbia, including in the USA. Such transfers rely on the safeguards provided by the Law (Arts. 64 and 65), such as these providers' standard contractual clauses.
6. Security
All traffic uses HTTPS only. Passwords, API keys and verification codes and links are stored only as cryptographic hashes. Documents are accessible only to the customer they belong to and to a recipient holding a valid signed link. We apply rate limiting, account lockout after failed sign-ins, the “I am not a robot” check, least-privilege database access and a strict content security policy.
7. Your rights
Under the Law you have the right of access (Art. 26), rectification and completion (Art. 29), erasure (Art. 30), restriction of processing (Art. 31), data portability (Art. 36), objection to processing based on legitimate interest (Art. 37) and withdrawal of consent where processing relies on it. Send your request to podrska@calculus.rs; we answer without undue delay and within 30 days at the latest. To protect your data we may ask you to confirm your identity.
If you are an IOS recipient or a person named in an IOS, for the data the customer entered in the IOS please contact the customer (your business partner) as the controller first; we will help them answer your request.
You have the right to lodge a complaint with the Commissioner for Information of Public Importance and Personal Data Protection, Bulevar kralja Aleksandra 15, 11000 Belgrade, www.poverenik.rs.
8. Required data
An email address, company name and password are required to open an account; without them no account can be opened. The note and the PDF attached to an IOS answer are optional.
9. Changes
We may change this policy. The current version is always on this page with its effective date. We will inform customers of material changes by email or when they sign in.