GST Gst on rent

#1
I have a small proprietorship firm with turnover of around 12 lac per annum. Since My sales are local as well as other states GST registration became necessary.
I also get Rs 10000/- monthly rental income by letting out a part of the industrial building. The tenant is running a small Lathe workshop engaged in local repair work and is not registered with GST.
My query:
Will GST be levied on this rental income also or it will be treated as NA being below the threshold of 20 Lacs per annum
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