Last yr I paid 50K capital gains tax. This yr I've 200K unrealized capital loss. If I realize some of this cap loss can I get some of last yr's paid cap gains tax back?

[Critter-3]

Short answer ... NO. What happens in 2022 cannot affect 2021. 

[Hal_Al]

Any  losses realized in 2022, and not used in 2022, will automatically carry forward to 2023 and beyond.  But, 2022 losses cannot be carried back.

[NCperson]

@hemandave80 unfortunately, it is a one way street:

As noted, if you had a big gain last year and a big loss this year, you can NOT use this year's loss to offset last year's gain

HOWEVER, let's say it was the other way around:

if you had a big NET LOSS last year (which creates a loss carry forward), and had a BIG gain this year, you could carry the loss FORWARD to offset the gain.

 but you can't carry the loss BACKWARDS to offset the gain, hence a 'one way street'

[fanfare]

If you did this in Futures (Sec 1256) then you could carry back losses.

This treatment is not available for stocks and bonds