# FinCalculator India — Full Specification & Financial Calculation Formulas

> Complete reference manual of mathematical formulas, Indian tax rules, compounding algorithms, and API parameters for LLM agents.
> Source: https://fincalculator.in
> Full Index: https://fincalculator.in/llms.txt

---

## 1. Mutual Fund SIP & Compounding Formulas

### A. SIP Future Value (Annuity-Due Formula)
For regular periodic investments (daily, weekly, monthly, quarterly, yearly) where payments land at the start of each period:

$$\text{FV} = P \times \left[ \frac{(1 + r)^n - 1}{r} \right] \times (1 + r)$$

Where:
- $P$ = Investment amount per period in ₹
- $r$ = Periodic interest rate = $\text{Annual Rate} / 100 / \text{Payments per Year}$
- $n$ = Total number of payments = $\text{Years} \times \text{Payments per Year}$

### B. Step-Up SIP Algorithm
Contribution increases annually by a percentage $S\%$ or fixed amount $A$:
- Year 1: Monthly contribution = $P$
- Year $k$: Monthly contribution = $P \times (1 + S/100)^{k-1}$ (or $P + (k-1) \times A$)
- Each year's 12 monthly contributions compound continuously until total tenure ends.

---

## 2. Sukanya Samriddhi Yojana (SSY) Rules & Math

- **Deposit Period:** 15 years from account opening.
- **Maturity Period:** 21 years from account opening.
- **Interest Rate:** 8.2% p.a. (Govt set, compounded annually).
- **Limits:** Min ₹250, Max ₹1,50,000 per financial year.
- **50% Higher Education Withdrawal:** Up to 50% of previous year-end balance withdrawable when the girl child turns 18 years old.

### Math Model (Years 1 to 21):
- For $y \le 15$: $\text{Balance}_y = (\text{Balance}_{y-1} + \text{Deposit}) \times (1 + r)$
- For $16 \le y \le 21$: $\text{Balance}_y = \text{Balance}_{y-1} \times (1 + r)$ (No deposits, pure compounding)

---

## 3. Equity Capital Gains Tax Formulas (Budget 2024 Amendments)

Applicable on listed equity shares and equity-oriented mutual funds (effective July 23, 2024):

### A. Long-Term Capital Gains (LTCG) — Section 112A
- **Holding Period:** $> 12$ months
- **Tax Rate:** 12.5%
- **Annual Tax-Free Exemption:** ₹1,25,000 per financial year
- **Formula:**
  $$\text{Taxable LTCG} = \max(0, \text{Gross Gain} - \max(0, 1,25,000 - \text{Prior Claimed Exemption}))$$
  $$\text{Base LTCG Tax} = \text{Taxable LTCG} \times 12.5\%$$
  $$\text{Total Tax} = \text{Base LTCG Tax} \times 1.04 \quad \text{(Includes 4\% Cess)}$$

### B. Short-Term Capital Gains (STCG) — Section 111A
- **Holding Period:** $\le 12$ months
- **Tax Rate:** 20%
- **Exemption:** Nil
- **Formula:**
  $$\text{Base STCG Tax} = \max(0, \text{Gross Gain}) \times 20\%$$
  $$\text{Total Tax} = \text{Base STCG Tax} \times 1.04 \quad \text{(Includes 4\% Cess)}$$

---

## 4. Indian Income Tax Slabs (New Tax Regime — FY 2026-27 / Tax Year 2026)

- **Standard Deduction:** ₹75,000 for salaried employees and pensioners.
- **Net Taxable Income Slabs:**
  - Up to ₹3,00,000: Nil
  - ₹3,00,001 to ₹7,00,000: 5%
  - ₹7,00,001 to ₹10,00,000: 10%
  - ₹10,00,001 to ₹12,00,000: 15%
  - ₹12,00,001 to ₹15,00,000: 20%
  - Above ₹15,00,000: 30%
- **Section 87A Tax Rebate:** Full tax rebate up to ₹60,000 if taxable income $\le \text{₹12,00,000}$ (making income up to ₹12.75 Lakhs effectively tax-free for salaried individuals).
- **Health & Education Cess:** 4% on net tax liability post-rebate.

---

## 5. Loan EMI Amortization Formula

$$\text{EMI} = P \times r \times \frac{(1 + r)^n}{(1 + r)^n - 1}$$

Where:
- $P$ = Loan Principal amount in ₹
- $r$ = Monthly interest rate = $\text{Annual Rate} / 12 / 100$
- $n$ = Loan tenure in months = $\text{Years} \times 12$
- **Total Payment:** $\text{EMI} \times n$
- **Total Interest:** $(\text{EMI} \times n) - P$

---

## 6. Open REST API Specifications

All endpoints return edge-cached JSON responses with CORS headers (`Access-Control-Allow-Origin: *`):

1. **SIP API:** `GET https://fincalculator.in/api/v1/sip?investment=10000&interest=12&years=10&frequency=monthly`
2. **EMI API:** `GET https://fincalculator.in/api/v1/emi?principal=5000000&interest=8.5&years=20`
3. **SSY API:** `GET https://fincalculator.in/api/v1/ssy?yearlyInvestment=150000&girlAge=1&rate=8.2`
4. **Capital Gains API:** `GET https://fincalculator.in/api/v1/capital-gains?buyValue=500000&sellValue=850000&holdingMonths=24`
5. **Income Tax API:** `GET https://fincalculator.in/api/v1/income-tax?grossIncome=1500000&regime=new-2026-27`

---

## 7. Legal Disclaimer

fincalculator.in is an independent private utility website and is NOT affiliated with the Income Tax Department of India, Ministry of Finance, Reserve Bank of India, or EPFO. Calculations are provided for educational and estimation purposes only. Zero personal user data is stored.