benefit deductions when 26 pay periods and 25 check dates

Hello, I wanted to ask how do you handle benefit deductions especially FSA deductions that have an annual pledge when there are 26 pay periods but only 25 check dates in a calendar year and the 26th check date falls in the following year. We'd like to make sure that full annual pledge is deducted in a calendar year and hits correct balances and W2. We use payroll interface and not payroll for NA. Thank you for your help!