IT-112-R(NJ): Tax amount - TP should not be greater than the tax imposed by other state.

Line 24a is looking for how much the NJ tax liability is on the same income. It can be equal or less than the NJ tax but it can't be more.

For example:

Let's pretend NJ tax liability is $1,000. Then line 24a should be $1,000. It does not matter that you paid in $1,500. All that matters is the actual tax liability. 

You pay tax to NJ so NY is giving credit for the double taxed income. The income to each state is different so the tax liability is a little different. Some states tax income the federal does not. For example: NJ taxes money you set aside in your retirement plan.  

Please enter the actual tax liability. To locate the tax liability for NJ, follow these steps:

1. Log into your return
2. Select state taxes
3. Enter the non-resident NJ for which you need the liability
4. On the left, go to Tax Tools
5. Select Tools
6. Select View Tax Summary
7. You will see Summary of your NJ Return at the top.
8. Locate the line that says Total Tax
9. Note that number
10. Return to your resident NY return and enter that number where it asks for the NJ liability.