First you must add the amounts determined in steps 2 and 3. If this total is more than the initial amount from step 1, you cannot claim a credit. If the total from steps 2 and 3 is less than the amount from step 1, you can claim a credit.
If you qualify, the credit is 15% of the total of steps 2 and 3. The amount of your Credit for the Elderly or the Disabled cannot exceed your total tax for the year.