Wow, is that incredibly mislabeled! My wife and I reversed engineered what was going on, and realised that it is the "state and local AND MORTGAGE INTEREST". In otherwords, the sum of those two lines is maxed at $10k.
Example 1:
Charity $300
Mortgage Interest: $18,200
Realestate Taxes: $9,000
State and Local Taxes: $12,000
State & Local > $10k: -$11,000
Total: $28,500
In reality, what is going on is:
Example 2:
Charity $300
Mortgage Interest: $18,200
Realestate Taxes: $0
State and Local Taxes: $10,000
State & Local > $10k: -$0
Total: $28,500
Notice that in example 2, the sum of Realestate and State & Local is capped at $10,000.
The line labeled "State & Local > $10k" should say "The amount you would have been able to deduct if Trump hadn't changed the tax code."
