I filed my 2019 return and now Im going in to REFILE and transfer my tuition credits to my dad. When I get to the page it keeps saying $0.00 is available, why?

[TurboTaxHeba]

If you have changed your income, the software will recalculate the amount required from your tuition amount to bring your non-refundable tax credit to zero. This means you might not have any tuition amount left to transfer to your dad. 

CRA wants you to reduce the none-refundable tax credit to zero, NOT the taxes to zero. Which means it is very common to get a huge refund if you have a current or carryforward amount. You will understand it from schedule 11:

Line 5 is your income Line 6 is your non-refundable tax credits (without your tuition)

Line 7 is the difference between Lines 5 and 6 (no negative amounts) You will need to use your current and unsued tuition amount to bring Line 7's value to zero:

1. You apply your unused tuition amount first (Line 1) > report on Line 8
2. Then you use from your current tuition amount (Line 4) >report on Line 10 
3. The total amount used is reported in Line 11. 

You will not be able to carry forward or transfer any amounts until you bring Line 7 to zero first.

Then you can use section B of schedule 11 to determine the unused or transfer amounts. 

What might have happened in the past with your prior tax returns, is that you didn't have enough income to produce an amount in Line 7 > your Line 7  was always zero or with low amount> Therefore, you were able to transfer or carry forward your tuition amount.  Please check the example below for clarification:

I hope this was helpful