The SET-Plan declaration of intent for ocean energy has set ambitious targets for wave and tidal energy technologies. Tidal technologies are expected to reach a levelised cost of energy (LCOE) of 15 cEUR/kWh by 2025. To meet this target, technology costs need to be reduced by about 75 % from 2016 values. Cost-reduction of tidal technologies is expected to go hand in hand with technology deployment and further technology validation gained by the operation of first-of-a-kind tidal farms. In this paper we assess the learning investment needed to support the cost-reduction of tidal energy to meet the 2025 SET-Plan targets. The learning investment necessary to bring tidal energy to cost-competitiveness would be of about EUR 1.45 billion, requiring about 3.2 GW of installed capacity to achieve the LCOE target of 15 cEUR/kWh. Supporting the step growth for the sector requires the design of accompanying policies aimed at the industrialisation of the sector to support the creation of assembly and manufacturing facilities.