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Forgot to File a Quasi-Final Tax Return—The 4-Month Deadline and Risks of Delay

2026年7月10日 09:58

While people know about the "3-month" deadline, the "4-month" one is often overlooked

When it comes to inheritance deadlines, many people think of the "3 months for inheritance renunciation." This 3-month period is relatively well-known.

However, the "4-month deadline" that follows is surprisingly overlooked. That is the quasi-final tax return.

"Why would a final tax return be necessary if the person has passed away?"—you might think so. However, the obligation to file a tax return for the income of that year remains for the deceased, and the heirs must perform this on their behalf. In this article, we will organize the deadlines and risks associated with this quasi-final tax return.

What is a quasi-final tax return?

A quasi-final tax return is a final tax return that heirs file on behalf of the deceased for their income in that year (from January 1st to the date of death).

Item Details Target Income Income from January 1st to the date of death Deadline for filing and payment Within 4 months from the day after learning of the start of inheritance Person filing Heirs (joint signature of all, or each person files individually)

While a regular final tax return is due between "February and March of the following year," a quasi-final tax return is characterized by a unique, shorter deadline of "4 months from the date of death."

Why is it so often overlooked?

There are reasons why the quasi-final tax return is easily forgotten.

Assuming that "death means no tax return is needed"
It is overshadowed by the 3-month (inheritance renunciation) and 10-month (inheritance tax) deadlines, making the 4-month one less noticeable
Not knowing about the quasi-final tax return system itself
Being busy with funerals and various procedures, and realizing the deadline has passed

Four months from the date of death passes in the blink of an eye in practical terms. The deadline approaches while you are busy identifying heirs and grasping the assets.

There are surprisingly many people who "need to file a quasi-final tax return"

Even if you think "it doesn't apply to us," you must file if the following applies.

Main cases requiring a filing Supplement Had real estate income Landlords who managed rentals generally need to file Had business income/capital gains Gains from real estate sold while alive are also subject Salary income over 20 million yen, or salary from multiple sources High-income earners or those with multiple income sources Public pension income over 4 million yen Likely to apply to elderly pension recipients

In particular, those who owned rental properties or had high pension income will, in most cases, need to file a quasi-final tax return. If the inherited real estate includes apartments or rental houses, you should consider it almost certainly subject to this.

The "3 risks" of forgetting

Neglecting to file a quasi-final tax return can lead to the following disadvantages.

Risk Details: Unfiled Return Penalty: A penalty for failing to file within the deadline. Delinquent Tax: Added to the tax amount, charged like interest based on the number of days the payment is late. Missing Out on Refunds: You will be unable to receive tax that should have been returned to you.

The third point is particularly wasteful. A quasi-final tax return is not just for "paying" taxes, but also for "receiving refunds."

Cases where "filing results in a refund"

It is not uncommon for taxes to be refunded when filing a quasi-final tax return. Typical cases include the following:

High medical expenses were paid before death (Medical Expense Deduction)
Income tax was withheld from pensions or compensation
Applying various deductions results in a refund of overpaid taxes

In other words, if you do not file because it is "too much trouble," you will not only face penalties but also miss out on money that should have been returned to you.

Note that only medical expenses paid up to the date of death are eligible for the medical expense deduction. Please be aware that medical expenses paid by surviving family members after the death are not eligible for the quasi-final tax return.

Supplementary points to keep in mind

In practice, it is also reassuring to keep the following points in mind:

If the deceased was a taxable business operator (including rental businesses), a quasi-final consumption tax return may also be required
Those who have renounced their inheritance are not obligated to file a quasi-final tax return (they are excluded from the filing obligation)
If there are multiple heirs, the principle is for all to sign jointly, but each can also file individually

Mark the "4 months" on your calendar

A quasi-final tax return is a procedure that requires caution; if you are unaware of it, you may overlook it, and if you forget it, you may face penalties. It is unavoidable, especially in inheritances involving real estate income or large pension income.

The deceased's income must be reported within 4 months of death
Landlords and those with high pension income are generally subject to this
Forgetting leads to additional taxes and delinquent taxes. You will also miss out on refunds
If you had high medical expenses, you might even get a refund by filing

When an inheritance occurs, we recommend marking three deadlines on your calendar right away: 3 months (for renunciation), 4 months (for the quasi-final tax return), and 10 months (for inheritance tax). To avoid losses due to "not knowing," checking early is essential.

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