Start with households by vehicle tier
A total vehicle count is not enough. Use current management records to count households with two, three, and four or more vehicles.
Record no-car and one-car households separately when they are not charged, and decide how exemptions and operational vehicles are treated.
- Two-car households
- Three-car households
- Four-plus-car households
- Exemption and registration rules
Use the same fee definition for both policies
The calculator treats each entered fee as the total monthly amount paid by one household in that tier, not a price for every vehicle.
Label Policy A as the current plan and Policy B as the proposal, then apply both to the identical household counts.
Example: 180 households at 10,000 won
Charging 180 two-car households 10,000 won produces 1.8 million won per month and 21.6 million won per year from that tier. A 20,000-won alternative produces 3.6 million won per month.
Repeat the calculation for higher tiers and add them to compare total monthly and annual revenue.
- Monthly revenue = households × monthly household charge
- Annual revenue = monthly revenue × 12
- Policy difference = Policy B - Policy A
Revenue is not the same as parking improvement
Higher fees do not create physical spaces. Measure registration and overnight occupancy on the same basis before and after implementation to assess behavior change.
Unregistered vehicles, exemptions, arrears, and ownership changes are excluded. Review bylaws and the required decision process separately.
Prepare the source data before comparing policies
Choose one date for the vehicle register and count registrations by household. Check duplicate temporary registrations and vehicles left behind by former residents so the affected household count is not inflated. Keep visitors, accessible vehicles, and management vehicles in separate columns when the proposed policy treats them differently.
Write Policy A and Policy B in the same table: charges for the second, third, and fourth-plus vehicle, exemptions, grace periods, and any prorating for mid-month changes. A price comparison is misleading when the covered vehicles differ. Use the same month for the register and billing data so estimates can later be reconciled with actual collections.
- Use one vehicle-register date
- Separate duplicate, former-resident, and exempt vehicles
- Describe both policies with identical tiers and scope
Enter household tiers and compare A with B
Enter the number of two-, three-, and four-plus-vehicle households, then the total monthly household charge for each tier under both policies. If a three-car household pays 10,000 won for the second car and 30,000 for the third, enter the 40,000-won household total. Confusing a per-vehicle price with a tier total can materially overstate or understate revenue.
Review monthly revenue, annual revenue, and the change between policies by tier before reading the combined total. For 180 two-car households at 10,000 won and 45 three-car households at 40,000 won, each tier contributes 1.8 million won per month, or 3.6 million combined. Create a conservative case by applying a realistic collection rate separately when exemptions or arrears are expected.
- Enter the total monthly charge for a household in the tier
- Review each tier before the combined total
- Compare full collection with a conservative collection case
Evaluate behavior change, not revenue alone
If the objective is less congestion, revenue is not the success measure. For four weeks before and a comparable four weeks after implementation, count parked vehicles, double parking, unregistered vehicles, and visitors at the same weekday and late-night time. Revenue may rise without a meaningful fall in overnight occupancy.
A reduction in multi-vehicle registrations may also reflect moves, vehicle sales, seasonality, or a new nearby public lot. Record occupancy and resident-count changes alongside the policy date. The calculator models money; fairness, bylaw validity, privacy, and the required decision procedure need separate review.
- Repeat late-night counts under matching conditions
- Measure revenue, registrations, and congestion separately
- Record external changes and complete governance review
Meeting checklist and practical FAQ
A resident or board briefing should show the number of affected households, monthly change by tier, estimated revenue, and intended use of the money on one page. State whether one-car households are unchanged and give a concrete example of the new amount for a two- or three-car household. Include the calculation date and source-register date.
Build the FAQ around real operations: replacement vehicles, long absences, rental and company cars, motorcycles, exemptions, and mid-month registration. When the estimate differs from a bill, recheck the household tier, total-versus-per-vehicle definition, exemptions, and prorating first. The adopted bylaw and official notice control the final charge.
- Show affected households and monthly differences
- Label dates, sources, and assumptions
- Document exceptions and mid-month rules in the FAQ