As long as SEP 401K contributions for tax year 2019 are made prior to April 15, 2020 (with any extensions), does it matter when the contributions for 2019 are made? When going through TurboTax if I indicate contribution to a plan the max limit is higher (takes into employee 25% + catch-up + employer contributions); compared to if I answer No contributions, but Yes to planning on making a contribution (the max on planning appears to be 25% employee). Related question, to maximize contributions do I need to contribute and then file taxes after the contribution?