PolicyEngine

Dark teal graphic titled "The next chapter of TAXSIM" with subtitle "In partnership with NBER." Left side describes it as an open-source, drop-in replacement for TAXSIM35 powered by PolicyEngine's microsimulation engine, with a link to policyengine.org/us/taxsim. Right side shows a terminal window with install command "pip install policyengine-taxsim," usage example, compatibility badges for CLI, Python, R, Stata, SAS, and Julia, and validation note showing 1,000+ test scenarios passing. PolicyEngine and NBER logos at bottom.

We've partnered with @nber.org to build the next chapter of TAXSIM — an open-source, drop-in replacement powered by PolicyEngine's microsimulation engine.

Works with CLI, Python, R, Stata, SAS, and Julia.

Try it here: policyengine.org/us/taxsim

Claude Code using PolicyEngine plugin.

We just launched a plugin that brings PolicyEngine to Claude.

Describe any tax or benefit reform in plain English. Claude runs a full microsimulation using our open-source model — 4,000+ variables, 65,000+ parameters, all 50 states.

No code required.

policyengine.org/us/claude-pl...

Claude Code with the PolicyEngine plugin.

We just launched a plugin that brings PolicyEngine to Claude.

Describe any tax or benefit reform in plain English. Claude runs a full microsimulation using our open-source model — 700+ variables, 1,200+ parameters, NI to UC.

No code required.

policyengine.org/uk/claude-pl...

Utah SB60 would cut the state income tax rate from 4.5% to 4.45%, reducing revenues by $84 million in 2026.

Who benefits? 53% of Utahns, with higher earners saving more in absolute terms.

Our analysis breaks down winners by income decile: policyengine.org/us/research/utah-sb60-income-tax-reduction

Happy holidays from PolicyEngine 🎄

This Giving Tuesday: GiveCalc is live at givecalc.org

A free PolicyEngine calculator showing how charitable donations affect your taxes.

🇺🇸 Federal + state tax savings (all 50 states)
🇬🇧 UK Gift Aid relief (including Scotland)

Know the true cost of giving → givecalc.org

BREAKING: PolicyEngine's microsimulation model projects a surge in candy consumption in the coming hours.

Happy Halloween! 🎃

Testing multi-agent AI workflows for policy research | PolicyEngine UK A multi-agent Claude Code system fared better on distributional analysis than benefit interactions; insights inform our forthcoming plugin.

We tested whether Claude Code's multi-agent system could automate parts of policy research.

Three specialized agents handled data fetching, script writing, and report generation. Here's what we learned: policyengine.org/uk/research/...

Marginal tax rates in California's proposed billionaire tax | PolicyEngine US The 5% tax creates marginal tax rates between 50% and 60% on wealth between $1 billion and $1.1 billion.

California's proposed billionaire tax creates marginal rates of 50-60% on wealth between $1.0-$1.1 billion due to its phase-in structure. We analyzed the math behind Initiative 25-0024: policyengine.org/us/research/...

PolicyEngine 2.0 and the future of public policy analysis Discover PolicyEngine's Latest Innovations in Evidence-Based Policy Analysis.

📍 London | 25th September | 12:00-18:00 | Central Hall Westminster

PolicyEngine 2.0 and the future of public policy analysis

Join us for live demos, breakthrough research presentations, and networking with leaders shaping evidence-based policymaking.
www.eventbrite.co.uk/e/policyengi...

How would changing the VAT threshold from £90k affect revenues?

Our new firm microsimulation model shows:
• £70k threshold: +£640m revenue
• £100k threshold: -£370m revenue
• £120k threshold: -£1.1bn revenue

All estimates for 2026-27.

🤝 Big news: PolicyEngine and @nber.org
have signed an MOU to ensure researchers worldwide continue accessing critical tax microsimulation tools.

We're building an open-source TAXSIM emulator, combining NBER's 50+ years of tax expertise with modern open-source infrastructure.

National Science Foundation awards PolicyEngine $300,000 grant | PolicyEngine US NSF's Pathways to Enable Open-Source Ecosystems program will support PolicyEngine's work to expand access to policy analysis tools.

🎉 PolicyEngine has been awarded a $300,000 Phase I POSE grant from NSF (Award No. 2518372) to expand our open-source platform, build sustainable governance, and grow our contributor community! https://policyengine.org/us/research/nsf-pose-phase-1-grant

Analyzing Energy Policy with PolicyEngine | PolicyEngine US We provide an Earth Day recap of our capabilities in the US and UK.

How do energy policies like carbon taxes, LIHEAP, or EV credits impact households? We recap PolicyEngine's open-source tools for analyzing these effects in the US & UK.

Learn more in our latest post, featuring insights from the Open Sustainability Policy Summit:
policyengine.org/us/research/...

Just back from EA Global SF with the @policyengine.org team! Incredible conversations with folks tackling the world's most pressing problems. With AI transforming society at unprecedented speed, our work on transparent policy simulation feels more urgent than ever.

Introducing GiveCalc | PolicyEngine US Calculate the true cost of charitable giving.

A fun new tool from @maxghenis.bsky.social : a calculator for charitable contributions, including both state and federal effects and interactions with other deductions. Lots of other good bells and whistles. @nicduquette.bsky.social should be into this.

policyengine.org/us/research/...

3. max ghenis - 2025.1.8 YouTube video by free equitism

🎉 Our CEO @maxghenis.bsky.social joined the Free Equitism podcast to discuss how PolicyEngine's microsimulation tools compute economic policy impacts.

Watch the full discussion here or on your favorite podcast platform: youtu.be/XWZA_mzxDXw?...

PolicyEngine US Launches Behavioral Responses | PolicyEngine US We've expanded our modeling framework to capture how policy changes affect labor supply.

Read our explainers:

🇺🇸 policyengine.org/us/research/us-behavioral-responses
🇬🇧 policyengine.org/uk/research/behavioural-responses

Thanks @arnoldventures.bsky.social for supporting!

🆕 PolicyEngine now supports behavio(u)ral responses in both the US and UK!

Choose default elasticities around how much policy affects work hours, or set your own.

New AI feature helps people understand their taxes and benefits | PolicyEngine UK We’re applying large language models to clarify complex policy rules.

Making benefit calculations crystal clear for everyone. See how our AI-powered explanations help you understand your Universal Credit, National Insurance Contributions, and more.
policyengine.org/uk/research/...

Global Trends in Government Innovation 2024 Governments worldwide are transforming public services through innovative approaches that place people at the center of design and delivery. This report analyses nearly 800 case studies from 83 countr...

The OECD's new report highlights how governments are translating regulations into executable code to make public services more consistent, transparent and efficient. This is exactly why we're building PolicyEngine!

Read more: www.oecd.org/en/publicati...