jp-estimated-tax

Section 1 -- Quick reference

Quick reference table

Field	Value
Country	Japan
Tax	Estimated income tax prepayments (予定納税 / yotei nozei)
Primary legislation	Income Tax Act (所得税法), Arts. 104-108, 111
Supporting legislation	National Tax General Act (国税通則法), Arts. 60-63
Authority	National Tax Agency (国税庁 / NTA)
Portal	e-Tax (etax.nta.go.jp)
Currency	JPY only
Payment schedule	Two instalments: 1/3 by July 31, 1/3 by November 30; final 1/3 with return (Feb-Mar)
Computation basis	予定納税基準額 (baseline amount) from prior year final return
Minimum threshold	JPY 150,000 baseline amount
Contributor	Open Accountants Community
Validated by	Pending -- requires sign-off by Japanese zeirishi (税理士)
Validation date	Pending

Instalment schedule summary

Instalment	Due date	Amount
1st (第1期)	1-31 July	1/3 of baseline
2nd (第2期)	1-30 November	1/3 of baseline
Final (確定申告)	16 Feb - 15 Mar (next year)	Actual tax minus yotei nozei paid

Conservative defaults

Ambiguity	Default
Baseline amount unknown	Request prior year final return -- do not estimate
Capital gains in prior year	Verify exclusion from baseline (should be excluded)
Income dropping	File reduction application (減額申請) before reducing payments
Blue return status	Does not affect yotei nozei schedule
Disaster circumstances	Flag for zeirishi -- special provisions may apply

Section 2 -- Required inputs and refusal catalogue

• Minimum viable input — The 予定納税基準額 (baseline amount) from the prior year final return (確定申告). (Minimum viable)
• Recommended inputs — Nature of income, withholding tax (源泉徴収) credits, blue return (青色申告) status, current year income trend. (Recommended)
• Ideal inputs — Complete prior year 確定申告, NTA notification of yotei nozei amounts, bank statements showing prior payments. (Ideal)
• Refusal policy if minimum is missing — HARD STOP. Without the baseline amount, yotei nozei cannot be computed.
• R-JP-ET-1 -- Cross-border income — Trigger: client has foreign-source income with treaty credits. Message: "Cross-border income and treaty credit timing for yotei nozei are outside this skill."
• R-JP-ET-2 -- Non-resident estimated tax — Trigger: non-resident client. Message: "Non-resident estimated tax is outside this skill."
• R-JP-ET-3 -- Corporate estimated tax — Trigger: client asks about corporate prepayments. Message: "Corporate estimated tax has different rules. This skill covers individuals only."

Section 3 -- Payment pattern library

This is the deterministic pre-classifier for bank statement transactions. When a debit matches a pattern below, classify it as a yotei nozei payment.

3.1 NTA income tax debits

NTA income tax debits pattern table

Pattern	Treatment	Notes
税務署 (zeimusho / tax office)	Yotei nozei payment	Match with July/November timing
予定納税, 予定	Yotei nozei payment	Explicit description
所得税 (shotokuzei / income tax)	Yotei nozei payment	Match with timing -- could also be final payment
申告所得税	Yotei nozei payment	"Declared income tax"
振替納税 (furikae nozei)	Yotei nozei payment	Direct debit for tax (debit typically ~1 month after due date)

3.2 Timing-based identification

Timing-based identification table

Debit date range	Likely payment	Confidence
1 July -- 10 August	1st instalment (第1期)	High if payee is tax office
Late July -- early August	1st instalment via 振替納税 (direct debit)	Debit date is later than due date
1 November -- 10 December	2nd instalment (第2期)	High
Late December	2nd instalment via 振替納税	Debit date is later
16 February -- 15 March	Final return payment (not yotei nozei)	Flag separately

3.3 Related but NOT yotei nozei

Related but not yotei nozei table

Pattern	Treatment	Notes
消費税 (shouhizei)	EXCLUDE	Consumption tax payment
住民税 (juuminzei)	EXCLUDE	Resident tax (municipal)
国民健康保険 (kokumin kenko hoken)	EXCLUDE	National health insurance
国民年金 (kokumin nenkin)	EXCLUDE	National pension
加算税 (kasanzei)	EXCLUDE	Penalty surcharge
延滞税 (entaizei)	EXCLUDE	Delinquent tax interest
還付金 (kanpukin)	Flag for reviewer	Tax refund

3.4 Payment method references

Payment method references table

Reference pattern	Treatment	Notes
e-Tax + 所得税 + 予定	Yotei nozei via e-Tax	Electronic payment
納付書 (nofusho)	Yotei nozei via payment slip	Bank counter payment
クレジットカード + 国税	Yotei nozei via credit card	Via NTA credit card site
Pay-easy + 国税	Yotei nozei via Pay-easy	Electronic banking

Section 4 -- Worked examples

Example 1 -- Standard two-instalment computation

Instalment table

Instalment	Period	Amount
1st (第1期)	July 2025	JPY 200,000
2nd (第2期)	November 2025	JPY 200,000
Final return	Feb-Mar 2026	Actual tax - JPY 400,000

Baseline amount (予定納税基準額) = JPY 600,000.

Example 2 -- Below threshold

Input: Baseline amount = JPY 120,000.

Output: Below JPY 150,000 threshold. No yotei nozei required.

Example 3 -- Delinquent tax computation

Input: 1st instalment JPY 200,000 due 31 July. Paid 15 October (76 days late).

Computation:

• First 60 days: JPY 200,000 x 2.4% x 60/365 = JPY 789
• Remaining 16 days: JPY 200,000 x 8.7% x 16/365 = JPY 762
• Total delinquent tax = JPY 1,551

Example 4 -- Bank statement classification

Input line: 2025/07/31 ; 振替納税 所得税予定1期 ; 出金 ; -200,000 ; JPY

Classification: Yotei nozei, 1st instalment for 2025. Tax payment -- not a deductible business expense.

Section 5 -- Computation rules

5.1 Baseline amount (予定納税基準額)

• Baseline amount formula — baseline = prior_year_tax_on_recurring_income - withholding_on_recurring_income if baseline >= 150,000: yotei_nozei required else: no yotei_nozei
• Baseline composition — The baseline is computed from the prior year's final return: income tax on recurring income sources minus withholding credits on those sources.
• Excluded from baseline — Capital gains from asset sales, retirement income, timber income, one-off income.

5.2 Instalment amounts

• Instalment amount formula — each_instalment = baseline / 3
• Instalment fraction — Each instalment is exactly 1/3 of the baseline (not 1/2).

5.3 Final return reconciliation

• Final return reconciliation formula — actual_tax = income_tax + special_reconstruction_tax (復興特別所得税) total_yotei_paid = 1st + 2nd instalments if actual_tax > total_yotei_paid: balance due with final return if actual_tax < total_yotei_paid: refund via final return

Section 6 -- Penalties and interest

6.1 Delinquent tax (延滞税 / entaizei)

Delinquent tax rate table

Period	Rate (2025)
First 2 months from due date	2.4% per annum (特例基準割合, reviewed annually)
After 2 months	8.7% per annum (standard rate)

6.2 No penalty surcharge (加算税)

• No penalty surcharge applies — Yotei nozei is not subject to penalty surcharges (加算税) because it is a prepayment, not a return-based assessment. Only delinquent tax (延滞税) applies.

Section 7 -- Reduction application (減額申請)

7.1 When to apply

When to apply table

Trigger	Action
Current year income significantly lower	File 予定納税額の減額申請書
Business closed or suspended	File reduction application
Disaster or extraordinary circumstances	File reduction application
New dependents or increased deductions	File reduction application

7.2 Application deadlines

Application deadlines table

Instalment	Deadline
1st instalment reduction	By 15 July
2nd instalment reduction	By 15 November

7.3 Process

• Reduction application process — 1. Complete 予定納税額の減額申請書 2. Attach estimated income statement through 30 June (for 1st) or 31 October (for 2nd) 3. Submit to jurisdictional tax office (所轄税務署) 4. Tax office reviews and approves or denies If the NTA determines the estimate was unreasonably low, penalties may apply.

Section 8 -- Edge cases

No prior year return. No yotei nozei obligation. Tax settled entirely through final return.

Capital gains from asset sales are excluded from baseline by definition. If incorrectly included, contact tax office for correction.

File 減額申請 by 15 July (1st) or 15 November (2nd). Flag for zeirishi.

Special deferral or reduction provisions under the Disaster Tax Relief Act (災害減免法). Flag for zeirishi.

Actual debit date is typically about 1 month after official due date. No delinquent tax for the gap between the official due date and the debit date.

Section 9 -- Self-checks

Before delivering output, verify:

• 予定納税基準額 confirmed from prior year return
• JPY 150,000 threshold checked
• Instalments correctly calculated as 1/3 each (not 1/2)
• Capital gains, retirement, one-off income excluded from baseline
• Reduction application deadlines identified if applicable
• Delinquent tax rates current for the applicable year
• Payment method appropriate for the amount (convenience store cap JPY 300,000)
• 振替納税 timing noted if applicable
• Special reconstruction tax included in final reconciliation
• Output labelled as estimated until zeirishi confirms

Section 10 -- Test suite

Test 1 -- Standard computation

Input: Baseline = JPY 600,000. Expected: 1st = JPY 200,000 (Jul). 2nd = JPY 200,000 (Nov). Final = actual - JPY 400,000.

Test 2 -- Below threshold

Input: Baseline = JPY 120,000. Expected: No yotei nozei required.

Test 3 -- Delinquent tax (76 days late)

Input: JPY 200,000 paid 76 days late. Expected: First 60 days at 2.4%, remaining 16 days at 8.7%. Total approx. JPY 1,551.

Test 4 -- First year

Input: New freelancer, no prior return. Expected: No yotei nozei. Tax paid with final return.

Test 5 -- Reduction application

Input: Baseline JPY 600,000. Client expects 50% income drop. Expected: Flag for zeirishi. File 減額申請 by 15 July or 15 November.

Test 6 -- Refund on final return

Input: Yotei nozei paid JPY 400,000. Actual tax JPY 300,000. Expected: Refund JPY 100,000 claimed on final return.

Prohibitions

• NEVER compute yotei nozei without confirming the 予定納税基準額
• NEVER include capital gains, retirement, or one-off income in the baseline
• NEVER forget that each instalment is 1/3 (not 1/2) of the baseline
• NEVER advise filing a reduction application without flagging for zeirishi review
• NEVER apply penalty surcharge (加算税) to yotei nozei -- only delinquent tax (延滞税) applies
• NEVER present amounts as definitive -- advise confirmation with zeirishi

Disclaimer

This skill and its outputs are provided for informational and computational purposes only and do not constitute tax, legal, or financial advice. Open Accountants and its contributors accept no liability for any errors, omissions, or outcomes arising from the use of this skill. All outputs must be reviewed and signed off by a qualified professional (such as a zeirishi or equivalent licensed practitioner in your jurisdiction) before filing or acting upon.

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