Complete Guide to Taxes, Year-End Adjustments, and Tax Returns for Private Used Car Transactions [2025 Edition]

When buying and selling a used car between individuals, multiple taxes such as income tax, capital gains tax, automobile tax, and environmental performance tax come into play. The responsibilities differ between the seller and the buyer, and the tax procedures that need to be handled also vary significantly. This chapter organizes the overall picture of taxes involved in person-to-person transactions.

The most important point in used car transactions is whether the profit from the sale is subject to taxation. In fact, in many cases, the sale of a used car by an individual is not subject to income tax. The reason is that the sale of movable property necessary for daily life is generally treated as non-taxable. However, there are cases where it may be subject to taxation depending on the use of the vehicle and the amount of profit generated, so it is extremely important to verify this in advance.​

For the buyer, a new tax called "Environmental Performance Tax" is involved during the ownership transfer. This tax was introduced in the October 2019 tax reform and replaces the former "Automobile Acquisition Tax." It is levied based on the current value (acquisition price) of the purchased used car, and if the acquisition price is 500,000 yen or less, it is exempt from taxation.​

Year-end adjustment and final tax return may sound similar, but they are completely different procedures. Year-end adjustment is mainly a procedure that company employees go through at their company every December or January to finalize the settlement of income tax withheld from their salary. On the other hand, final tax return is a procedure performed by self-employed individuals, people with side business income, or those who have earned investment profits—in cases where there is income other than salary income.​

Capital gains generated from the private sale of a used car are not subject to year-end tax adjustment. In other words, even if you are a salaried employee, you may need to file a separate tax return if you realize a profit from the sale. However, in most cases, if the vehicle was used for daily life purposes such as commuting to work or school, or shopping, you will not need to file a tax return even if a profit is generated from the sale.​

If a salaried employee earns income outside of their main job, there is a special provision that eliminates the need for a tax return if that side income is less than 200,000 yen. However, in the case of capital gains from selling a used car, this 200,000 yen rule may not apply, so caution is necessary. If you are uncertain, we recommend consulting with the tax office in advance or confirming with a tax accountant.​

The most important determination point is whether the used car being sold qualifies as "household movable property." According to the National Tax Agency's standards, if a vehicle was used for purposes normally necessary for daily life, such as commuting to work or school or everyday shopping, no income tax is imposed on profits from its sale. This applies if the vehicle was used within the scope of daily necessities, such as transporting family members or weekend outings.​

On the other hand, vehicles primarily used for hobbies or leisure purposes are treated differently. When selling sports cars, classic cars, campers, luxury foreign cars, or other vehicles not directly necessary for daily life results in a profit, that profit is highly likely to be subject to taxation. Additionally, when sole proprietors sell vehicles used for business purposes, these are not recognized as household goods, and the profits obtained are subject to taxation as transfer income.​

The important thing to note is that even if you make a profit from the sale, you won't be taxed unless the amount exceeds a certain threshold. As will be explained in detail in the section on calculating capital gains, profits of 500,000 yen or less are tax-exempt due to the special deduction.​

Buyers need to consider different types of tax burdens than sellers. The main taxes incurred at the time of purchase are the "Environmental Performance Tax" and the "Automobile Tax (Type-based Tax)". The Environmental Performance Tax is paid during the name transfer procedure at the Land Transport Bureau, and since it is paid at that time, it is not subject to income tax filing.​

The environmental performance tax rate varies depending on the fuel efficiency of the purchased vehicle, ranging from 0% to 3%. However, if the acquisition price is 50,000 yen or less, it is completely tax-exempt, so this tax does not apply when purchasing inexpensive used cars. Vehicles with good environmental performance (hybrids and eco-cars) often have lower tax rates.​

Automobile tax (type levy) is a tax imposed on the owner as of April 1st each year. It operates on a system where the full year's amount is paid at once, and in cases of mid-year sales, monthly proration settlement occurs. In private sales, it is important for the seller and buyer to thoroughly discuss in advance who will bear the unused portion.​

If the title transfer is not properly completed, tax notices will continue to be sent to the previous owner, leading to significant issues. Situations such as being refused fuel at gas stations or being unable to have the vehicle inspected may also occur. The buyer must promptly complete the title transfer procedures after acquisition and receive the new vehicle registration certificate.​

The basic formula for calculating capital gains is as follows. The process involves subtracting the acquisition cost and transfer expenses from the sale amount, then applying a special deduction of 500,000 yen.

Acquisition cost refers to the vehicle's base price at the time of purchase, and may also include option fees and registration costs at the time of purchase. Transfer expenses are costs directly incurred for the sale, such as advertising fees, brokerage commissions, and sales agency service fees. However, in typical private sales, transfer expenses are often minimal or nonexistent.​

The special deduction limit of 500,000 yen applies to the total of all capital gains for that year. In other words, if you have transfers of land, buildings, stocks, golf club memberships, or other assets in addition to the sale of a car, the 500,000 yen is deducted from the combined total of all capital gains. Special attention is required when there are multiple asset sales.​

To illustrate with a specific example, let's consider a case where a recreational vehicle purchased for 3.5 million yen was sold for 5 million yen. The calculation in this case would be "5 million yen - 3.5 million yen - 500,000 yen = 1 million yen," meaning 1 million yen is recognized as taxable capital gain.​

Even more important is the difference in tax rates based on the ownership period. If the ownership period is 5 years or less as of January 1st of the year of sale, the entire amount calculated as "short-term capital gains" will be subject to taxation.

On the other hand, for long-term ownership exceeding 5 years, it is classified as "long-term capital gains," and taxes are applied to half of the capital gains. In the example of 1 million yen mentioned above, if owned for 5 years or more, taxes would be levied on 500,000 yen, resulting in significant tax savings.​

Whether you need to file a tax return depends on the purpose of the vehicle you sold and the amount of profit you earned.

First, if you sell a vehicle primarily used for daily purposes such as commuting to work or school and everyday shopping, you do not need to file a tax return regardless of whether you made a profit. This criterion applies to most people. If you're selling a typical household light vehicle or passenger car, you can generally assume that filing a tax return is not necessary.​

On the other hand, caution is required when selling vehicles intended for leisure or sports purposes (such as sports cars, convertibles, or camping cars) and a profit is generated. This type of vehicle is not recognized as household property, so if a profit exceeding 500,000 yen occurs, there is an obligation to file a tax return. Additionally, filing a tax return is mandatory when a sole proprietor sells a vehicle that was used for business purposes.​

For employees who have income other than their main job, generally speaking, if the total income exceeds 480,000 yen, it becomes subject to tax filing. This is because the basic deduction amount is 480,000 yen. However, in the case of transfer income from used car sales, the application of this standard may differ slightly, so verification is important.​

If you are a company employee who has undergone year-end tax adjustment and have earned capital gains income from selling a used car, you will generally need to file a separate tax return. This is because year-end tax adjustment is a system that only covers employment income, so capital gains income is completely excluded.​

After receiving year-end tax adjustment from your company, you will need to prepare a capital gains tax return during the tax filing period (February 16 to March 15) and submit it to the tax office. You must prepare necessary documents such as your My Number card and have supporting documentation for capital gains, such as sales contracts, readily available.​

If the ownership period, including both primary and side business use, exceeds 5 years, the long-term capital gains tax rate applies, so it's helpful to verify this in advance for a smooth filing process. Especially when selling an older vehicle, check the purchase date to see if you're eligible for preferential tax rates.​

When filing a tax return for capital gains from selling a used car, there are several main documents you need to prepare. The first required document is the "Tax Return Form," which can be downloaded from the National Tax Agency's website or obtained at tax office counters. Due to tax reforms in 2023, the former "Tax Return Form A" was abolished and unified.​

Next, you will need a document called "Statement of Details of Transfer Income." In this document, you record details about the vehicle you sold (make, model year, mileage, etc.), the sale amount, the purchase price, and transfer expenses. This makes it easier for tax office staff to review and ensures a smooth audit process.​

As supporting documents at the time of sale, a copy of the "sales contract" and the original "receipt" are required. In the case of private sales, there are transactions where no contract exists, but you must always provide documentary proof when filing. To prevent future disputes, it is strongly recommended to create a contract at the time of the transaction and keep a copy.​

You will need either a My Number Card, or a My Number notification card along with identification documents (such as a driver's license). If you use e-Tax (electronic filing), having a My Number Card is more convenient. For mailing or submitting in person to the tax office, attach a copy of your My Number Card with your submission.​

There are three methods for filing your tax return. You can use e-Tax (internet filing), submit in person at the tax office, or mail your return. e-Tax offers the advantage of being able to file 24/7 and provides smooth payment processing. Submitting in person at the tax office has the benefit of being able to consult with staff about any questions on the spot. Regardless of the method chosen, the filing deadline is annually from February 16th to March 15th. If you miss this deadline, your return will be treated as a "late filing," which may result in late payment penalties and fines, so caution is necessary.​

When a sole proprietor sells a business vehicle, accounting procedures are required in addition to calculating capital gains. Unlike regular individuals, since this is the sale of a business asset, it must be recorded in the books and reflected in the financial statements.​

If you use a vehicle for both business and personal purposes, a process called "apportionment" is required. In practice, if you regularly apportion expenses at a fixed ratio, you calculate the transfer income using that same ratio. For example, if the usage is 40% for work and 60% for private purposes, 40% of the sale amount is treated as a transfer of business assets.​

Even for sole proprietors, if the transfer income is 500,000 yen or less, a special deduction applies and no income tax payment is required. However, if the transfer income results in a loss (when the sale amount is below the acquisition cost), there is an advantage of being able to offset that loss against business income profits through "loss offsetting." This is a special provision not available to general individuals earning salary income. Furthermore, if the loss is large and the overall business income becomes negative, you can also utilize the "carryforward deduction" system, which allows you to carry forward that loss for up to three years.​

In private used car transactions, disputes frequently arise over prepaid expenses such as "automobile tax," "weight tax," "compulsory liability insurance premiums," and "recycling tickets," rather than taxes themselves. All of these are expenses already paid by the previous owner, and because there are no clear rules about who should bear the burden after the sale, buyers and sellers often disagree.​

Automobile tax is assessed for a full year to the owner as of April 1st, and tax notices are sent around May. When selling a car mid-year, it is common practice for the buyer to pay the seller on a prorated monthly basis for the unused portion of the tax that the seller has already paid, corresponding to the months the buyer will use the vehicle. For example, if selling in July, the amount equivalent to 8 months from August to the following March is typically calculated and paid separately.​

Regarding automobile weight tax and compulsory automobile liability insurance premiums, these are typically valid until the next vehicle inspection and have already been paid in full by the seller. In this case, there are two patterns: either the buyer pays for the unused portion, or it remains the seller's responsibility. As a customary practice, it tends to be more common for the seller to bear these costs.​

The recycling certificate is a document that proves the vehicle disposal fee was paid in advance at the time of new car purchase. It is mandatory for all vehicles registered after September 2004, and ownership transfers to the buyer upon sale. Typically, the recycling fee equivalent is included in the sale price, so requesting additional payment after the sale often leads to disputes.​

The most reliable way to prevent these issues is to clearly specify the responsibility for each cost in the sales contract. By writing down agreements in advance such as "Automobile tax: buyer pays prorated amount," "Weight tax and compulsory insurance: seller pays," and "Recycling certificate: buyer pays," you can prevent future disputes.​

Delays in title transfer are also a major cause of disputes. If the buyer neglects to complete the title transfer procedure after the transaction is finalized, the automobile tax notice will continue to be sent to the seller the following year. In this case, the seller continues to bear the tax obligation, which is highly inconvenient. Additionally, if the title remains under the previous owner's name, there is a risk of liability issues developing in the event of an accident. It is essential for the buyer to complete the title transfer procedure at the Motor Vehicle Registration Office within one month at the latest after the transaction is completed.​

When selling a kei car (light vehicle), there are several points that differ from regular passenger vehicles. For kei cars, the "Light Vehicle Tax" imposed on the owner has no refund system even if you cancel the registration mid-year. While regular passenger vehicles receive a prorated refund for the remaining months until year-end, kei cars do not have this system, making it particularly disadvantageous to sell near the end of the fiscal year. If you are considering selling your kei car, completing the procedure by the end of March will help you avoid being taxed for the following fiscal year.​

Regarding the environmental performance tax, there is a difference in tax rates between light vehicles and regular automobiles. Generally, light vehicles have lower tax rates, and eco-friendly vehicles receive even more preferential treatment. However, if the acquisition value is 500,000 yen or less, both light vehicles and regular automobiles are tax-exempt.​

Generally, no consumption tax is imposed on car sales between individuals. This is because private sales do not constitute a business. However, the situation differs when sole proprietors or corporations sell business-use vehicles. If they are taxable business operators with taxable sales exceeding 10 million yen, consumption tax (10%) may be imposed on the vehicle sale amount.​

Specifically, when a sole proprietor calculates consumption tax on a sale amount, they do not simply multiply the sale amount by 10%, but instead use a reverse calculation method: "sale amount ÷ 1.1 × 10%". For example, if sold for 1.1 million yen, the consumption tax would be "1.1 million yen ÷ 1.1 × 10% = 100,000 yen". Since consumption tax calculations are complex, if you are uncertain, we recommend consulting with a tax accountant or tax office.​

To proceed with confidence regarding taxes and tax filing in private used car transactions, there are several important points to keep in mind. First and foremost, create a sales agreement before the sale and clearly specify tax and cost responsibilities. Verbal agreements cannot prevent future disputes. Many free contract templates are available online, so we recommend creating one by referring to these resources.​

Second, it's important to keep accurate records of your vehicle's purpose and ownership period. Since determining "whether the vehicle is for personal use or hobby use" is crucial in tax audits, make sure you can explain the purchase date and actual daily usage. Additionally, for capital gains tax calculations, the tax rate varies significantly depending on whether the ownership period exceeds five years, so accurately tracking the purchase date can lead to tax savings.​

Third, if the capital gain is expected to exceed 500,000 yen, consult with a tax accountant or tax office in advance. This allows you to verify whether your calculations are correct and prevent discrepancies in the tax payment amount. Since tax offices are crowded during the tax filing period, completing advance consultations will make the process smoother.​

Fourth, it is essential to promptly complete the title transfer after the transaction is finalized. Both the buyer and seller must responsibly complete the procedures at the Land Transport Bureau within one month as an iron-clad rule. By mutually confirming that the title transfer has been completed, you can almost completely prevent subsequent troubles.​

A particularly important point to note regarding the 2025 tax filing system is that digitalization is advancing, and electronic submission of various documents is now recommended. The use of e-Tax is increasing, and filing via smartphone has also become possible. However, in the case of filing capital gains from used car sales, submission of supporting documents such as contracts and receipts is mandatory, so not everything can be digitized. Be prepared to submit the required documents either as originals or copies.​

The basic deduction amount is currently 480,000 yen, and if the total of capital gains and other income exceeds this amount, there is an obligation to file a tax return. Even for company employees with employment income, if capital gains occur, the determination is made based on the combined total, so caution is necessary.​

To accurately file your tax return, be sure to verify the following points. First, documentation supporting the acquisition cost. Having receipts or purchase agreements from the time of purchase is ideal, but if unavailable, there is also a tax estimation system that considers 5% of the sale amount as the acquisition cost. However, if you can prove the actual purchase amount, you can use the actual amount rather than the estimate.​

Second, determining whether it's short-term or long-term. Strictly verify how many years have passed since the purchase as of January 1st of the year of sale. Even if it's exactly 5 years, if it's less than 5 years as of January 1st, it will be treated as short-term. Since the tax rate changes significantly, an incorrect determination will result in a major loss.​

Third, check for overlap with other capital gains. If you sold land, buildings, stocks, or other assets during the year, the ¥500,000 special deduction applies to the total of all capital gains. When multiple assets are sold, calculate based on the combined amount.​

In this article, we have thoroughly explained taxes, year-end adjustments, and tax returns for peer-to-peer used car transactions. The most important message is that "most used car sales are not subject to taxation." If you sell an ordinary car that was used for commuting or daily shopping, you have no income tax liability, no matter how large the profit from the sale.​

However, the situation differs when selling hobby vehicles used for leisure or sports, luxury cars, or classic cars. In these cases, capital gains are generated, and if profits exceed 500,000 yen, tax filing and payment become necessary. Similarly, the sale of business vehicles by sole proprietors also requires mandatory tax filing.​

The difference between year-end adjustment and tax return filing is also important. Even for company employees, capital gains from selling a used car are not subject to year-end adjustment, and a separate tax return may be required. Documents must be submitted to the tax office during the filing period from February to March.​

The most common issues that arise in private vehicle sales are not related to income tax, but rather to prepaid expenses such as automobile tax and weight tax. Since there are no clear legal rules regarding these expenses, it is absolutely necessary to specify and agree upon them in advance in the sales contract. Similarly, delays in transferring ownership can cause significant problems, so be sure to complete the procedures promptly after the transaction is finalized.​

We recommend consulting with the tax office or a tax accountant in advance in case of emergencies. Since tax offices become crowded during the tax filing period, resolving all questions through prior consultation will help you respond calmly during filing. Even with the advancing digitalization in 2025, proper storage of supporting documents and accurate record-keeping remain the most important aspects. By keeping these points in mind, you can achieve safe and smart private used car transactions.