annual rental...is residencia reqd?

Long -term rental -- is residencia reqd? I plan to rent an appartment on an annual basis to live in on an ad hoc basis when I'm in Spain. Will this involve me in having to obtain a carta de residencia or will it still be considered a holiday rental? Will it involve me in the tax system? Obviously, I want to stay clear of the mind-numbing bureaucracy. I'd be very grateful for some advice on this matter. Thank you all in advance.