Oregon statewide transit tax applies before July 1, 2018, and the Vermont Child Care Contribution is 0 for all of 2024 (mid-year starts) #10213

Summary

Two state payroll contributions started on July 1, but their annual formulas read the parameter on January 1:

• Oregon: the parameter has no entry before July 1, 2018. backdate_parameters (policyengine_us/tools/parameters.py) extends the earliest value back to 2015-01-01, so the tax applies from 2015.
• Vermont: the explicit zero is in effect on January 1, 2024, so an annual period gets nothing for July–December 2024.

#10154 handles the same situation for WA Cares (July 1, 2023): wa_employee_long_term_care_contribution averages the rate in effect in each month of the year. That method would give half-year amounts for Oregon in 2018 and Vermont in 2024.

What the sources say

Oregon statewide transit tax: July 1, 2018

Current ORS 320.550 (2025 Edition):

A tax is imposed at the rate of one-tenth of one percent of the wages of an employee who is:

ORS chapter 320, 2017 Edition, PDF page 21, note after ORS 320.550:

Note: Section 122k, chapter 750, Oregon Laws 2017, provides:
Sec. 122k. Section 122a of this 2017 Act [320.550] applies to tax periods beginning on or after July 1, 2018.

Oregon DOR, 2018 Oregon Combined Payroll Tax Report Instructions, "Transit tax", PDF page 5:

The 2017 legislature passed House Bill 2017 which imposes a 0.1% transit tax on the wages of every Oregon resident, nonresidents of Oregon for services performed in Oregon, and periodic payments made under ORS 316.189. The new transit tax applies to tax periods beginning on July 1, 2018.

Oregon DOR, 2021 instructions, "Statewide transit tax", PDF page 6:

On July 1, 2018, HB 2017 went into effect requiring all employers to withhold, report, and remit one-tenth of one percent (0.001) of wages paid to their employees.

Vermont Child Care Contribution: July 1, 2024

32 V.S.A. § 10553 (chapter 246):

(a)(1) … An employer may deduct and withhold from an employee’s covered wages an amount equal to not more than one quarter of the contribution required pursuant to subsection (b) of this section.

(b) The contribution rate shall be 0.44 percent of each employee’s covered wages and 0.11 percent on each self-employed individual’s self-employment income.

Act 76 of 2023 (H.217), Sec. 47, "Effective dates", PDF page 73:

(6) Sec. 24 (Child Care Contribution) shall take effect on July 1, 2024.

Vermont Department of Taxes, GB-1326, PDF page 3:

Employers are required to pay a 0.44% payroll tax on their employees’ wages paid on or after July 1, 2024,

Reproduction (main, single filer, $50,000 wages)

from policyengine_us import Simulation
def run(st, y, v):
    s = Simulation(situation={"people": {"p": {"age": {y: 40}, "employment_income": {y: 50_000}}},
        "households": {"h": {"members": ["p"], "state_code": {y: st}}}})
    return s.calculate(v, y)[0]
print([run("OR", y, "or_employee_statewide_transit_tax") for y in [2015, 2017, 2018, 2019]])
print([run("VT", y, v) for y in [2024, 2025] for v in ["vt_employee_child_care_contribution", "vt_employer_child_care_contribution"]])

The half-year amounts assume wages accrue evenly over the year, as in #10154. The Vermont employee amount assumes the employer withholds the maximum quarter share, as PE already does.

Expected

• Add 0000-01-01: 0 before 2018-07-01 in the Oregon statewide transit rate.
• Apply the Oregon (2018) and Vermont (2024) rates to the months they are in effect, as Start CO FAMLI, Paid Leave Oregon and WA Cares at their program dates, and add 2019–2024 Washington PFML premiums #10154 does for WA Cares.