This article provides more details on the calculation of adjusted ADA for the 2021-2022 school year, and includes some sample calculations.
TEA has published the 2019-2020 attendance rates that will be used in the 2021-2022 ADA calculations for the first 4 six weeks periods of the school year. TEA will multiply actual cumulative ADA for the first 4 six weeks of this year by a ratio, which is the the 2019-2020 target percentage attendance rate (TPAR) attendance rate for your district divided by the actual 2021-2022 cumulative attendance rate for the first four six weeks. If the 2019-2020 TPAR is lower than the actual cumulative attendance rate for the first 4 six weeks of this year, the adjustment will not apply.
You can find that TPAR rate here. To find it, scroll down to "TPAR for SY2021-2022 Operational Minutes Adjustment" under "District and Charter Planning Tools." Use the rate for your individual LEA.
Note that special program ADA and FTE counts will also be adjusted by the same ratio. The adjustment will not apply to enrollment based counts like compensatory education or dyslexia education.
Thanks to Janét for putting these examples together.