The exercise price floor for zeisei-tekikaku stock options must equal or exceed the fair market value of the underlying share on the grant date. That sentence is a statutory requirement under Article 29-2 of the Sozei Tokubetsu Sochi Ho. What it does not tell you is how to calculate that fair market value for an unlisted company, which is where most founders need guidance.
For a publicly listed company, fair market value is straightforward: it is the market price of the share on the grant date, or an average of recent market prices per the relevant tax guidance. For an unlisted startup, there is no market price. The calculation must use one of the methods approved by the National Tax Agency (NTA), and the choice of method, as well as the quality of the inputs, determines whether the resulting exercise price will withstand scrutiny.
The three primary methods
The NTA's guidance on unlisted company share valuation draws substantially from the framework used for inheritance and gift tax purposes (sozoku zei / zoyo zei no hyoka), while also recognizing company-specific and industry-specific factors. The three primary methods relevant to startup option grant pricing are the net asset approach, the income approach, and a comparable company method.
The net asset approach (shisan ho) values the company based on its net assets at a given date, typically adjusted to reflect the fair value of each asset and liability rather than their book value. For a very early-stage company with limited assets, this often produces a relatively low per-share value, which is why it is commonly used at founding and in the early seed stage. The calculation is: adjusted net assets divided by total issued shares.
The income approach (shunyu kansan ho) estimates the present value of the company's future earnings or cash flows, discounted at an appropriate rate. For a pre-revenue startup, this method requires projections and assumptions that can be difficult to defend with precision. For a startup that has been operating for a year or two and has some revenue history to extrapolate from, income-based approaches become more defensible.
The comparable company method (ruiji kaisha hi ho) derives a value multiple from publicly traded companies in the same industry and applies that multiple to the subject company's financial metrics. This works best when clear public comparables exist, which is easier in some sectors than others. In Japan, the comparable company universe for some niche B2B SaaS categories is thin, requiring careful judgment about which public companies are genuinely comparable.
Which method applies when
The choice of method is not purely the company's preference. The NTA guidance and interpretive guidance from tax practitioners suggest that the appropriate method depends on the company's stage and the reliability of the inputs. For a very early company with essentially no operations, the net asset method is typically the most defensible because it is based on verifiable balance sheet data rather than projections. As the company develops a track record, income-based approaches become appropriate.
Many advisors use a blended approach: weight the net asset value and an income-based estimate, typically in proportions that reflect the company's maturity. A common blending approach for early-stage companies is 60 percent weight on net assets and 40 percent on income, shifting toward income weighting as revenue becomes more predictable.
The calculation and the choice of method must be documented. "We think our shares are worth 500 yen per share" is not a valuation for FMV purposes. The documentation should show the inputs used (balance sheet data, revenue projections, discount rate assumptions, comparable multiples), the method applied, the calculation, and the resulting per-share value.
Timing: when to calculate and how often
FMV for option grant pricing purposes is determined at the grant date. A valuation performed six months before the grant is not necessarily valid for grants issued at a later date, especially if the company's financial position or market conditions have changed materially.
For companies that issue options continuously throughout the year, as startups often do when hiring, the practical approach is to establish an FMV at the beginning of each grant tranche and use that price for all grants in the tranche. If a significant financing event occurs between grant cycles, such as a new investment at a materially higher valuation, the FMV should be recalculated before issuing the next tranche.
This creates a natural incentive to batch grants: issuing all options for a given quarter in one board resolution, at one exercise price based on one FMV calculation, is administratively cleaner than issuing options one at a time with individual valuations. Batching also reduces the accounting complexity around stock-based compensation expense recognition.
The relationship between investor valuation and FMV
A question that comes up often is whether the company's post-money valuation from its most recent investment round can be used as the FMV. The answer requires nuance. If an investor has just invested at a certain pre-money valuation per share, that price is a data point that informs the FMV calculation. But it is not automatically the same as the FMV for option grant purposes.
Investor valuations typically reflect preferred shares, which have liquidation preferences and other rights that common shares do not. The per-share price paid by an investor for preferred shares will be higher than the FMV of a common share (the class of share underlying most options) when those preference rights are factored in. The discount between preferred and common share FMV is a real quantity that requires modeling, and this modeling is standard practice in US 409A valuations. Japanese tax advisors take a similar approach, though the formal regulatory framework differs.
We are not saying founders should try to maximize the discount between investor price and common FMV to set artificially low exercise prices. We are saying that the relationship between investor price and common FMV is a legitimate technical question with a real answer, and that answer should be calculated and documented rather than assumed.
What happens if the FMV calculation is wrong
If a grant is later found to have an exercise price below the correctly calculated FMV at grant date, the grant does not qualify for zeisei-tekikaku treatment. The employee will owe income tax at exercise rather than capital gains tax at sale. The company may also face withholding tax obligations that were not anticipated when the grant was structured.
Correcting this after the fact is difficult. The options cannot simply be re-priced upward to match the correct FMV; that would change the terms of the grant and potentially trigger new tax events. In some cases, replacing the defective grants with new grants at the correct exercise price is the most practical path, but this means a higher exercise price for the employee, which reduces the economic value of the grant.
The downstream cost of an incorrect FMV calculation at grant time, in terms of unexpected tax obligations for employees and remediation work for the company, is high relative to the cost of doing the calculation correctly the first time. This is one of the areas where professional advice from a tax accountant (zeirishi) who has specific experience with startup equity and zeisei-tekikaku grants is genuinely worth the investment.
