The last day where contributions to an RRSP may be included in the 2018 tax year is March 1st, 2019 (you will receive a separate contribution receipt for contributions made between January 1st and March 1st).
Wealthsimple will honour deposits as being eligible to be allocated towards the 2018 tax year as long as the deposit is initiated by March 1st, 8:59:59 pm (EST). We recommend trying to beat the rush though!
If you are planning on making a withdrawal and would like the income to be counted towards 2018, you must initiate the withdrawal by December 30th, 2018.
Learn more on how to make a deposit to your Wealthsimple account here!