Korea Diesel Environmental Charge Proration and Prepayment Calculator

Why can a bill arrive after selling the car?

Korean diesel environmental improvement charges are billed after the period of ownership.
Selling or scrapping a vehicle does not erase liability for earlier use.
This calculator separates the two bills payable in 2026 so you can compare charged days with your ownership records.
A vehicle-tax receipt does not settle the environmental charge; check the charge name and assessment period independently.

Three numbers to compare

Check liable days, the estimated regular amount for those days, and the difference under a timely prepayment scenario.
An annual total alone can conceal differences in year-specific indices or a mid-period sale.

Your next action

Save the period comparison as TXT or print it, then compare it with the registration record and official bill.
Ask the municipality about ownership days, exemption recognition and any previous ad-hoc payment before interpreting a discrepancy as an unpaid balance.

2026 payment dates and the periods they cover

The first bill payable in March 2026 covers July 1–December 31, 2025, a 184-day half-year.
The second bill payable in September 2026 covers January 1–June 30, 2026, a 181-day half-year.
Their sum does not represent ownership during the January–December 2026 calendar year.
Ownership during the second half of 2026 belongs to a later payment cycle and is outside this comparison.

First bill: second half of 2025

Charge period: 2025-07-01 to 2025-12-31; regular payment window: 2026-03-16 to 2026-03-31.
Article 17 of the collection-processing rules assigns the index by assessment period, so this bill uses the 2025 index of 2.368.

Second bill: first half of 2026

Charge period: 2026-01-01 to 2026-06-30; regular payment window: 2026-09-16 to 2026-09-30.
This period uses the 2026 index of 2.406; the shared payment year does not justify applying that index to the first bill.

Vehicle inputs and exemption confirmation

First registration determines vehicle age; your acquisition date starts your ownership liability.
For a used car, these dates normally differ, and the purchase-contract date may differ from the ownership-transfer registration date.
Enter the registered total engine displacement as a whole number in cubic centimetres (cc).
Confirm the actual exemption and its dates rather than inferring it from model year.

Liable, exempt or unconfirmed

A confirmed exemption or exclusion covering the entire comparison period produces KRW 0; an unconfirmed status holds the amount.
Euro standards, emission-control equipment, disability, veteran status and livelihood vehicles involve specific requirements and recognition periods.

Exemption beginning during a period

Keep the vehicle marked liable and enter the municipality-confirmed first non-chargeable day.
An exemption that ends and resumes, or repeated ownership intervals, is outside this single-interval model.

Base amount, displacement and vehicle-age factors

The standard base is KRW 20,250 per half-year.
It is multiplied by the assessment-year index, displacement factor, vehicle-age factor and regional coefficient.
When an age threshold falls inside a half-year, the calculation changes the factor on the anniversary rather than applying the closing-day factor to the whole period.

Displacement thresholds

Up to 2,000cc uses 1.00; above 2,000 through 2,500cc uses 1.25; above 2,500 through 3,500cc uses 1.75.
Above 3,500 through 6,500cc uses 2.64; above 6,500 through 10,000cc uses 4.50; above 10,000cc uses 5.00.

Age thresholds

Age 3–under 4 uses 1.00; 4–under 6 uses 1.04; 6–under 8 uses 1.08; 8–under 10 uses 1.12; age 10 or more uses 1.16.
Under age 3, a vehicle confirmed to meet post-2006 manufacturing emission standards uses 0.50; otherwise it uses 1.00.
For a February 29 first registration, this model uses February 28 as the non-leap anniversary.
Check a bill at that boundary with the municipality.

Qualifying privately owned small truck

The KRW 7,600 base requires a general-type truck of no more than 3,000cc, with registered maximum payload of at least 800kg, and all statutory exclusions checked.
Commercial transport, relevant franchise-operator ownership, government ownership and corporate ownership are excluded.
A truck meeting post-2006 emission standards uses the standard base during the first three years after registration instead of this reduced base.

Confirm the regional coefficient and relocation date

The regional coefficient follows the registered location and statutory exceptions.
Population brackets are under 100,000: 0.40; 100,000–under 500,000: 0.85; 500,000–under 1 million: 0.87; 1–under 5 million: 1.00; and 5 million or more: 1.53.
The calculator uses a coefficient confirmed from the bill or municipality, not a live address or population lookup.

Why population alone is insufficient

County and qualifying township areas, former districts of merged cities and certain capital-region cities have special rules.
Do not mix commercial-transport exceptions into a private vehicle estimate without verifying its registered use.

A move during the assessment period

Enter the relocation registration date and the new coefficient; the new value applies from that date.
The actual moving date may differ from the registration change.
This model supports one coefficient change during ownership.

Daily proration and cutoff dates

Each unchanged-factor segment equals base × period-year index × displacement factor × age factor × regional coefficient × liable days ÷ total days in the half-year.
Your acquisition or transfer-in registration date is included; the transfer-out registration date is excluded.
For example, a sale registered on March 10, 2026 leaves the seller liable from January 1 through March 9: 68 days.
Acquisition and cutoff on the same day produce zero days; dates outside the assessment window do not contribute.

Records govern scrappage, deregistration and exemptions

Article 7 of the processing rules addresses evidence of discontinued use, including delivery to a scrapyard.
Enter the confirmed first excluded day.
The calculation ends the preceding day; do not automatically treat the deregistration date as the final included day.

Rounding and minimum notices

Segment amounts within a half-year are added before fractional won and the remainder below KRW 10 are discarded.
A regular bill below KRW 3,000 is shown as zero.
Municipal intermediate rounding and combined ad-hoc assessments may differ, so these are comparison estimates.
If a positive discounted installment falls below KRW 3,000, prepayment totals are held until combined-bill and minimum-notice treatment is confirmed.

January and March prepayment differ

Article 9(7) of the Environmental Improvement Costs Liability Act allows a 10% reduction on both the previous second half and the current first half for January prepayment.
March prepayment reduces only the current first-half charge by 10%, so the effective reduction on the total is not always 5%.
The two periods can have different indices, ownership days, age factors or regional coefficients.

Statutory windows and the 2026 notice

The statutory filing and payment windows are January 16–31 and March 16–31.
Seoul’s 2026 notice gives January 16–February 2 for January prepayment.
Confirm local application deadlines and procedures separately.
As of September 22, 2026, both prepayment windows have closed.

Conditions for comparison

The calculator does not offer automatic prepayment amounts for vehicles acquired on or after January 1, 2026.
A scenario is also unavailable if liability ended before its payment window.
Confirm that eligibility and timely filing/payment are assumed.
If a disposal cutoff is entered, the prepayment figure compares recalculated ownership liability; it is neither the original cash prepayment nor an actual refund calculation.

Worked example: a long-owned 1,998cc vehicle in Seoul

Assume a fictional liable standard diesel vehicle first registered and acquired on January 1, 2010, and owned throughout both assessment periods.
Its displacement factor is 1.00, age factor is 1.16 and confirmed regional coefficient is 1.53, with no exemption.
The example button fills these assumptions to demonstrate the calculation.
It does not look up your vehicle or establish its exemption status.

Regular total: KRW 171,570

The first period is KRW 85,105.2096 before truncation, displayed as KRW 85,100; the second is KRW 86,470.9182, displayed as KRW 86,470.
Even with the same vehicle factors, the period amounts differ because the annual indices differ.

January: KRW 154,410; March: KRW 162,920

January combines discounted installments of KRW 76,590 and KRW 77,820, a reduction of KRW 17,160 against regular payment.
March retains KRW 85,100 for the first bill and adds KRW 77,820 for the second, reducing the regular total by KRW 8,650.
These values verify this page’s sum-then-truncate convention and do not guarantee the municipality’s bill or refund.

How to use the comparison

First check the registration certificate and ownership record for first registration, transfer dates, engine size and vehicle use, then confirm exemption status and the bill’s assessment period.
Choose the municipality-confirmed regional coefficient and indicate continuous ownership, a sale or another cutoff reason.
Compare regular and prepayment scenarios, and expand the calculation segments to check factors against their effective dates.

A bill received after selling the car

Read the covered period rather than assuming the issue date proves an incorrect charge.
If days after transfer appear included, or a previous ad-hoc payment appears missing, ask for reconciliation and provide the receipt.

Helping an older family member

Separate vehicle-tax bills from environmental-charge bills, then check each period’s days and index individually.
The TXT report contains assumptions and source links so a family member or municipal officer can retrace the comparison.

Limits and preparation for an adjustment request

This tool models one continuous ownership interval for a private vehicle; repeated acquisition, repeated exemptions, multiple relocations and special commercial cases need separate review.
It excludes arrears surcharges, vehicle tax, early-scrappage subsidies, payment history and refund interest.
Confirm ambiguous registration or discontinued-use dates and any earlier ad-hoc assessment before treating the amount as settled.
Do not ignore a notice or pay an arbitrary calculator amount simply because the estimate differs.

Documents to prepare

Gather the bill’s dates and day count, registration history, transfer record or scrapyard/deregistration evidence, exemption decision and payment receipts.
For a relocation, confirm both the effective registration date and the old and new regional coefficients.

Statutory adjustment procedure

Decree Article 9 addresses official corrections of the liable party or calculation, including additional collection or refund.
Article 10 provides an adjustment application within 30 days of receiving a bill or installment notice.
An adjustment request does not change the payment deadline.
Ask the municipality about both the application and the payment procedure.

Frequently asked questions

Does this use the vehicle-tax prepayment discount?

No.
It applies the period-specific 10% rule in Article 9(7) of the Environmental Improvement Costs Liability Act.
Vehicle-tax rates are separate.

Can I simply subtract 5% for March prepayment?

That is only approximately appropriate when the two period amounts are equal.
March discounts the current first half by 10% after period ownership and the correct index are applied.

Why does a bill still arrive after a sale?

It can cover ownership before the sale because billing is in arrears.
Check whether days after transfer are included and whether an ad-hoc bill was already paid.

Should I enter the deregistration date for scrappage?

Evidence such as delivery to the scrapyard can determine the discontinued-use date.
Enter the municipality-confirmed first excluded day; the calculation ends the preceding day.

Is a newer diesel automatically exempt?

Model year alone is insufficient.
Confirm vehicle-specific emission standards, exemption conditions and the recognized period with the municipality.

Does a zero result prove exemption?

No.
Full-period exemption, zero liable days and a regular notice below KRW 3,000 are different cases.
Read the day counts and minimum-notice explanation.

Can I claim the 2026 prepayment discount now?

Both the January and March windows had closed by this page’s September 22, 2026 review date.
The scenarios assume timely payment then, and do not predict next year’s index or deadline.

Can I claim the difference from my bill as an immediate refund?

No.
The municipality must reconcile ownership, exemptions, intermediate rounding, minimum billing and payment history.
The saved report supports that review and is not a refund decision.

Official sources and rule dates

Sources reviewed September 22, 2026 through the National Law Information OPEN API.
This is a Korean-law calculator for bills payable in 2026.
The Act and Decree versions used took effect October 1, 2025.
The processing rules took effect November 5, 2025; Articles 7, 17, 18, 22 and 33-2 support the cutoff, index-year, rounding, minimum-notice and recalculation discussion.
The 2025 index applies January 1–December 31, 2025; the 2026 index applies January 1–December 31, 2026.
Annex identifiers checked: 17668449, 17682027 and 17682029.
The 2026 index API identifies Notice 2026-77 in its metadata and supplementary provisions; its amendment attachment uses a 2025-77 label.
The index 2.406 and January 1, 2026 effective date agree.
Future maintenance must recheck both year-specific indices, notices, coefficients and minimum-billing rules.

Prepare a period-by-period comparison

Confirm the vehicle and dates above, compare both assessment periods, and save the TXT report for your municipality.
For other decisions, use the separate vehicle-tax, ownership-transfer and scrappage calculators; do not combine their discounts or eligibility rules.

1. Vehicle and liability

2. Location, cutoff and payment