CPP-D back pay taxes

Ok im a bit concerned about paying taxes on the back pay. I received $$ for 2021, how do i go about now claiming that on last years taxes? I’m in the process of applying for DTC but in the mean time what shoukd i do? can i wait or must claim this right away? ugh

There is a way to have the back pay distributed to the years it should have been paid in.
I would phone the CRA.