Contributions to Keogh Plans must be made by: A December 31st of the calendar year in which the contribution may be claimed on that person's tax return B December 31st of the calendar year after which the contribution may be claimed on that person's tax return C April 15th tax filing date of the calendar year after which the contribution may be claimed on that person's tax return D August 15th tax filing date permitted under an automatic extension of the calendar year after which the contribution may be claimed on that person's tax return