Gst levied under the rack rate or actual amount

Under the GST law for hotel industry, it's classified the gst rates as per tariff. Now we collect the gst on rack rate or actual amount received . I give one example for clarification (1) We give the rack rate of 2499/- not exceeding the slab of 2500-7500, then the affected gst rate is 12% . If we collected and deposited the gst on rack rate or amount amount