The Peru-Chile border will be partially closed from December 26 to 29. According to El Comercio, road works will force the border to close from midnight until 7 am each day for the four-day period.
Thousands of people cross the border between Tacna and Arica each day, with numbers rising during holiday periods. If you do want to cross the border during this period, be prepared for delays. If you buy a bus ticket from Peru into Chile (or vice versa), make sure you arrive at the border when the road is open.