Terms of use

Effective from 7 October 2026 · version 2026-10-07

This is a translation. If the two versions differ, the Serbian version prevails.

1. Provider

The Calculus IOS service at ios.calculus.rs is provided by 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 (“Calculus”). By registering and using the service you accept these Terms and the Privacy policy. If you have a separate contract with Calculus, it prevails in case of conflict.

2. The service

The service lets users of the Calculus ERP deliver statements of open items (IOS) as PDF with accompanying data to their business partners (recipients); lets the recipient view the IOS through a link, accept or dispute individual items, add a note and attach one PDF; and lets the customer see the answer. Calculus is not a party to the reconciliation of receivables and payables between the customer and the recipient; the legal effects of an IOS and its answer are governed by their relationship and applicable law.

3. Account

• Accounts may be opened by legal entities and sole traders for business purposes. Registration data must be accurate.
• You are responsible for keeping your password and API key safe and for all actions taken with them. The API key is shown only once; do not share it and keep it only in your ERP. Report suspected misuse immediately to podrska@calculus.rs.
• Use “Remember me” only on devices that other people do not use.

4. Service limits

• Storage per customer: 25 MB; largest PDF: 20 MB. When storage is full, new documents are not accepted.
• Each document is available for 30 days from upload, after which it is permanently deleted together with its IOS data, the answer and the attached PDF. The service is not an archive: keep originals and answers in your ERP.
• A recipient can answer only once; a submitted answer is final.
• Requests are rate-limited, and an “I am not a robot” check is required in some cases.

5. Customer obligations

The customer agrees to:

• send only IOS documents and data for which it has a lawful basis and which it is authorised to deliver to the recipient, and to keep them accurate;
• send links only to the correct recipients (the link is the recipient's only means of access and is valid until the document expires);
• not upload malicious content, unlawful material or data unrelated to the IOS;
• not attempt to circumvent limits and protective measures, access other customers' data or disrupt the service.

6. Processing of personal data on behalf of the customer

For personal data contained in an IOS (creditor, debtor and line-item data, and the recipient's answer) the customer is the controller and Calculus the processor within the meaning of Art. 45 of the Serbian Law on Personal Data Protection. By these Terms the customer instructs Calculus to process that data solely to provide the service described in section 2. Calculus undertakes to:

• process the data only on this instruction and not use it for any other purpose;
• ensure that persons with access to the data keep it confidential;
• apply the appropriate technical and organisational security measures described in the Privacy policy;
• engage only the sub-processors named in the Privacy policy (Microsoft 365 for email, Cloudflare Turnstile for the “I am not a robot” check) and inform the customer of changes;
• assist the customer in responding to data subjects' requests and in meeting its security obligations;
• notify the customer of a personal data breach without undue delay;
• delete the data when the period in section 4 ends, or earlier at the customer's request;
• make available to the customer the information needed to verify these obligations.

7. Availability and liability

Calculus aims to keep the service available and working correctly but does not guarantee uninterrupted operation; it may be suspended temporarily for maintenance, updates or circumstances beyond our control. To the extent permitted by law, Calculus is not liable for indirect damage, lost profit, or the consequences of inaccurate data entered by the customer or of the recipient's answer. Liability for damage caused intentionally or by gross negligence is not limited.

8. Suspension and termination

Calculus may temporarily disable an account or API key on suspicion of misuse, a security threat or breach of these Terms, notifying the customer where possible. The customer may ask at any time to close the account at podrska@calculus.rs; the account and data are deleted as described in the Privacy policy.

9. Changes to the Terms

Calculus may change these Terms. The current version is always on this page. We inform customers of material changes by email or when they sign in; continued use after the changes take effect means accepting them.

10. Governing law and disputes

These Terms are governed by the law of the Republic of Serbia. Disputes fall under the competent court in Belgrade.