The Simplified Calculation Method and the Iterative Calculation Method are the only methods for with the IRS provides instructions, but are not guaranteed to give an optimal result because the iterative method does not always converge to a solution and instead defaults to a sub-optimal result. Any calculation method that satisfies the requirement that the sum of the PTC calculated on Form 8962 and the self-employed health insurance deduction does not exceed the amount of health insurance premiums is permitted. From IRS Pub 974:
CAUTION! Using the special instructions in this part is optional. If you are eligible for both a self-employed health insurance deduction and the PTC for the same premiums, you may use any computation method that results in reporting amounts that satisfy the rules for both the deduction and PTC, as long as the sum of the deduction claimed for the premiums and the PTC computed, taking the deduction into account, is less than or equal to the enrollment premiums.
