As a sole proprietor living in NYC, can I allocate my income between NYC-based clients and non-NYC based clients for determining Unincorporated Business Tax liability?

I'm a sole proprietor living in NYC, where I conduct all of my business (consulting services). However, my main client is based in another state and pays me from that other state. Can I allocate my income between income generated from NYC-based clients and non-NYC based clients for determining UBT liability? Or am I subject to the UBT on all of my income since I physically conduct all of my business in NYC? Thanks in advance for anyone who has insight on this.