international real estate firm that acts as an agent for buying, selling, and leasing properties for big industrial companies, has hired me for a consulting position.

An international real estate firm that acts as an agent for buying, selling, and leasing properties for big industrial companies, has hired me for a consulting position. The position involves designing the website, designing the marketing materials, designing the email broadcasts and assisting them with the real estate software tools that they use to identify and locate properties.

As far as I know at this moment they don't deal with mortgages, because the clients are big industrial companies. On the other hand what if the property being bought or sold is financed with interest, then that would mean that the commission they earn through being an agent is contaminated earnings and then they would pay me from that money. The company is owned by non-Muslims.

Additionally in some years, they get commission for lease/rental renewals and in some years the buying/selling dominates their income. All the properties are owned by their clients, they are just agents. Please advise. I got the offer today, and have been told to star April 17th, now I am having doubt about the position being halal or haram.