tax_calculator.js

function lmito(income, initial_value = 200, increased_value = 530,
    taper_one_start = 37000, taper_two_start = 90000, taper_in_rate = 0.03,
    taper_out_rate = 0.015) {
    if (income < taper_one_start) {
        return initial_value * -1;
    }
    else if (income >= taper_one_start & income <= taper_two_start) {
        let tapered_in_lmito = (initial_value + (income - taper_one_start) * taper_in_rate);
        if (tapered_in_lmito < increased_value) {
            return tapered_in_lmito * -1;
        }
        else {
            return increased_value * -1;
        }
    }
    else if (income >= taper_two_start) {
        let tapered_out_lmito = (increased_value - (income - taper_two_start) *
            taper_out_rate) * -1;
        if (tapered_out_lmito < 0) {
            return tapered_out_lmito;
        }
        else {
            return 0;
        }
    }
    else {
        return 0;
    }
}

function lmito_lab(income, initial_value = 350, increased_value = 927.5,
    taper_one_start = 37000, taper_two_start = 90000, taper_in_rate = 0.0525,
    taper_out_rate = 0.02625) {
    if (income < taper_one_start) {
        return initial_value * -1;
    }
    else if (income >= taper_one_start & income <= taper_two_start) {
        let tapered_in_lmito = (initial_value + (income - taper_one_start) * taper_in_rate);
        if (tapered_in_lmito < increased_value) {
            return tapered_in_lmito * -1;
        }
        else {
            return increased_value * -1;
        }
    }
    else if (income >= taper_two_start) {
        let tapered_out_lmito = (increased_value - (income - taper_two_start) * taper_out_rate) * -1;
        if (tapered_out_lmito < 0) {
            return tapered_out_lmito;
        }
        else {
            return 0;
        }
    }
    else {
        return 0;
    }
}


function lito(income, value = 445, taper_start = 37000, taper_rate = 0.015) {
    if (income < taper_start) {
        return value * -1;
    } else {
        let tapered_lito = (value - (income - taper_start) * taper_rate) * -1;
        if (tapered_lito < 0) {
            return tapered_lito;
        } else {
            return 0;
        }
    }
}

function value_of_bracket_cut(income) {
    if (income < 87000) {
        return 0;
    } else if (income > 90000) {
        return 135;
    } else {
        let base_tax = (income - 87000) * 0.37;
        let change_tax = (income - 87000) * 0.325;
        return base_tax - change_tax;
    }
}

function income_tax(income) {
    if (income <= 18200) {
        return 0;
    }
    let income_tax_owed = (income - 18200) * 0.19;
    return income_tax_owed;
}

function governments_plan(income) {
    let initial_value = 200;
    let income_tax_owed = income_tax(income) + lito(income);
    if (income_tax_owed < initial_value) {
        if (income_tax_owed >= 0) {
            return Math.round(income_tax_owed);
        } else {
            return 0;
        }
    } else {
        let total_benefit = lmito(income) * -1 + value_of_bracket_cut(income);
        return Math.round(total_benefit);
    }
}

function labors_plan(income) {
    let initial_value = 350;
    let income_tax_owed = income_tax(income) + lito(income);
    if (income_tax_owed < initial_value) {
        if (income_tax_owed >= 0) {
            return Math.round(income_tax_owed);
        } else {
            return 0;
        }
    } else {
        lmito_benefit = lmito_lab(income);
        let total_benefit = lmito_benefit * -1 + value_of_bracket_cut(income);
        return Math.round(total_benefit);
    }
}


function difference_between(income) {
    let output = {
        'income': income,
        'liberal': governments_plan(income),
        'labor': labors_plan(income),
        'difference': labors_plan(income) - governments_plan(income)
    };
    return output;
}