You have no choice to claim it all in the current year.
The IRS only allows you to claim up to $3,000 of capital losses against ordinary income in the current year.
Then for future years, you will first apply these
carried over capital losses against current year capital income. If there are
still capital losses available, you will be able to offset up to $3,000 of
ordinary income each year. Any remaining capital losses will be carried over to
future years to first offset future capital gains then up to $3,000 of ordinary
income.
Please refer to this IRS link for more information about capital gains and losses:
https://www.irs.gov/taxtopics/tc409.html
