I am changing my payroll schedule from the 15th of the month and the last day of the month, to every 2 weeks. I am using the year end as the time to make this switch. When I am setting up the new schedule in IOP, my first pay period end date is 1/10 and the first pay date is 1/17. When I set this up, IOP back dates my payroll to include 2019 dates (12/28/19 - 1/10/20). I don't want to include 2019 dates but I cannot figure out how to adjust this in in IOP.
Currently, the ability to manually override the pay period in running your first paycheck for 2020 is not available. You can leave it as is. What is important is the tax year of paycheck date which falls on 2020. This affects the employee's taxable income not the pay period.
If you pay employees on the last day of December for this work, the paycheck date of December 31, 2019, and this would mean the pay is taxable income in 2019. However, since your first paycheck date falls on January 17, 2020, this mean that the employee's pay is taxable income in 2020.