Arthea
Field Notes

Plain writing on money, markets, and the math that runs your future.

No jargon and no sales pitch — the ideas a Canadian household needs to pressure-test a plan, and an honest way to think about uncertainty.

Taxes & benefits

The surtax on a comfortable retirement; how the OAS clawback works, and why your RRIF quietly triggers it

The OAS clawback is a 15% surtax that starts at $95,323 of net income in 2026 — and the RRIF withdrawals you're forced to make can walk you straight into it. Here's the mechanism, and the levers.

Charan A. · Jul 26, 2026 · 6 min read
Read the piece →
01Latest writing All Retirement planning Investing & wealth building Taxes & benefits Inside Arthea
Taxes & benefits

The tax move most Canadian DIYers miss; which account holds which asset

Interest in your RRSP, U.S. dividends out of your TFSA, Canadian dividends in non-reg — asset location is the tax move most Canadian DIYers never make. Here's the map.

Jul 13, 2026 · 5 min
Investing & wealth building

Lump sum vs. dollar-cost averaging

We modelled $100,000 deployed lump sum vs. dollar-cost averaging. The difference; $282. The real cost,$64,572, comes from leaving it in cash. Here's why.

Jul 12, 2026 · 5 min
Inside Arthea

How Arthea protects your financial data

Arthea is built so no one, not even us, needs to know who you are. Here's how your financial data is protected, what we don't collect, and where our protections stop.

Jul 11, 2026 · 4 min
Inside Arthea

How Arthea builds and backtests retirement forecasts

We backtested our retirement forecasts against real history — and one landed at the 0th percentile. Here's how the math works, and where it breaks.

Jul 10, 2026 · 7 min
Retirement planning

The most dangerous number in your retirement plan

A free retirement calculator hands you one clean line to age 95. That single number is the most dangerous part of your plan. Here is why, and how to test for it.

Jul 9, 2026 · 5 min