"If you count $4000 in the first quarter it is going to get "annualized" to $16,000 which already exceeds the cap."
That's a good point. I forgot that the amounts get annualized by multiplying by the annualization factor. Perhaps it makes more sense to put an upper limit on the SALT deduction each quarter of $10,000 divided by the annualization factor: $2,500 for Q1, $4,167 for Q2, $6,667 for Q3 and $10,000 for Q4.
