According to a Notice 2018/11763 in the Official Gazette the investment allowance rates for the 2019 assessment year.

Companies Allowance Rate Applies on
13.50% Investments in patents; environmentally friendly R&D; and energy saving and ventilation systems in hotels, restaurants, and bars;
3% Reuse of containers/packaging;
30% Investment in seagoing vessels (maritime shipping).
Small companies 13.50% For digital investments;
20.50% For investments in security;
8% For other investments up to 31 December 2017, and 20% from 1 January 2018 to 31 December 2019; and
20% For investments in patents; environmentally friendly R&D; and energy saving and ventilation systems in hotels, restaurants, and bars; and for digital investments from 1 January 2018 to 31 December 2019.