This is the most up to date information as of November 2017, those of us who already own property in Turkey or have a residency permit know that the Turkish Government change or update the rules and regulations often for foreigners.
You can own a property in Turkey and do not need to have a residency permit if you don’t want to. You are allowed to enter Turkey and stay for a maximum of 3 months using your 90 day multi entry tourist visa in a 180 day period. If you want to apply for a residency visa you will need to apply for it within 1 month of your entry. You can apply for a 1 year residency visa or a 2 year visa which is the maximum visa allowed to date.
If you do not want a residency visa you can simply leave Turkey for 24 hours by visiting another country, on return to Turkey you can pay for another 3 month visa currently costing a UK citizen 20USD. From the Aegean coast you can take a short boat trip to the Greek Islands of Kos or Rhodes for example, Kos is a mere 1 hour if you are in Bodrum. If you are on the Mediterranean coast in Alanya you can take a ferry trip to Northern Cyprus which takes around 3 hours.
If you overstay your time in Turkey once your visa has run out and you have not applied for a residency permit you will be fined and possibly banned from entering Turkey. If the overstay is more than 10 days it can become a huge problem. The fines and bans are usually imposed at border control as you try to leave Turkey and you will be told there what your fine is and if a ban is to be carried out. But, if you caught by the police for example after an, overstay of 10 days or longer you could be arrested, fined and deported and the ban will be enforced for much longer. The cost of the fine depends on the length of overstay and which country you are from.
If you reside full time in Turkey foreigners can now leave Turkey and stay out of the country for as long as you like, as there is no longer a time restriction on returning. However, if your residency is up for renewal and you miss the deadline to renew, you will lose all your previous continuous residencies year on year, which go towards applying for your long term residency. You can apply for your long term residency after 8 years continuous residency without any breaks. If you reside in Turkey then you will obviously need a residency permit and if you want to buy a phone or a car you will most definitely need one.
Applying for a residency permit is not a difficult process, you will need to show certain documents and you will have an interview at your local Immigration Office.