If you are merely letting out the property and enjoying the rent as an individual or as a company, in most cases, you will need to mention rental income under the head “income from house property” in the income-tax return (ITR) form. It doesn’t matter whether it’s a house (residential) or an office (commercial). The same would hold true if the taxpayer is running a paying guest house (without a hotel licence), letting out the property on platforms such as Airbnb.
Rental income can be business income when, say, a business and its assets are leased as a going concern, or assets are leased along with furniture and fittings and other associated structures, or in addition to leasing properties, various other services are regularly provided (like lifts, security, or other amenities such as machinery, canteen, housekeeping, etc).