Information from the Swedish Tax Agency:

The ROT deduction will revert to 30 percent of the labor cost on January 1, 2026.

To be granted a 50 percent ROT deduction, payment must have been made no later than December 31, 2025. The application must have been submitted to the Swedish Tax Agency by January 31, 2026, and the work must be completed when the application is submitted.

In Next Project, the update from 50% to 30% will be adjusted on December 30, 2025. 

If you wish, you can adjust to 30% earlier yourself by going to Administration-Finance-Tax Reduction, selecting ROT in the upper section, and in the lower section changing the value in the percentage column from 50 to 30, then clicking Save.