To make the PTET election an estimated payment must be made by June 15th of the tax year in question so if that was not done the first available option is for the 2024 tax year. Generally the PTET election is not recommended unless the tax savings would be material. Tax savings are computed by taking your expected taxable income multiplied by the CA PTE rate of 9.3% (your deduction) then multiplying this by the federal rate (37% is the max rate). Potential costs incurred to make the conversion to S corporation should be factored in to determine if the tax savings are worthwhile.