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monteplan

Monte Carlo financial planning simulator for Python.

monteplan models accumulation and decumulation with realistic taxes, multiple spending policies, multi-asset correlated portfolios, and professional reporting. Use it as a Python library, CLI tool, or interactive Streamlit web app.


Key Features

  • Monte Carlo Engine -- Vectorized numpy simulation with monthly time steps and deterministic seeding
  • 4 Return Models -- Multivariate normal, Student-t (fat tails), historical block bootstrap, Markov regime switching
  • 5 Spending Policies -- Constant real, percent-of-portfolio, Guyton-Klinger guardrails, VPW, floor-and-ceiling
  • Tax-Aware Withdrawals -- US federal progressive brackets, LTCG rates, RMD enforcement, configurable withdrawal ordering
  • Multi-Account Support -- Taxable, traditional (401k/IRA), and Roth accounts with distinct tax treatment
  • Guaranteed Income -- Social Security, pensions, and annuities with COLA adjustments
  • Stress Testing -- Market crashes, lost decades, high inflation, and sequence-of-returns risk scenarios
  • Sensitivity Analysis -- One-at-a-time tornado charts and 2D heatmaps
  • Antithetic Variates -- Variance reduction for tighter confidence intervals
  • Streamlit App -- Interactive web UI with Plotly charts, scenario comparison, and CSV export

Quick Start

from monteplan.config.defaults import default_plan, default_market, default_policies, default_sim_config
from monteplan.core.engine import simulate

result = simulate(default_plan(), default_market(), default_policies(), default_sim_config())
print(f"Success probability: {result.success_probability:.1%}")

See the Installation guide to get started, or jump straight to the First Simulation walkthrough.


Try It Now

Open in Colab


Documentation Overview

Section Description
Getting Started Installation, quick start, first simulation walkthrough
User Guide Detailed coverage of every feature
Notebooks Interactive Colab-ready tutorials and case studies
Case Studies Real-world planning scenarios with analysis
Math & Assumptions Model formulas, assumptions, and limitations
API Reference Auto-generated from source docstrings

Disclaimer

This is an educational tool for exploring financial planning concepts. It is not financial advice. Results are simulations based on simplified models and assumptions. Consult a qualified financial advisor for real planning decisions.