Why I Skip the TSP L Funds and Stay 100% in the C Fund

When you sign in-processing paperwork, the TSP defaults you into an L Fund. Nobody explains what's actually in it. I checked mine, didn't like what I saw, and moved everything into the C Fund. Eight years and $781,000 later, I still haven't touched an L Fund again.

The Default Everyone Gets Handed

The L Funds — Lifecycle Funds — are built to be a set-it-and-forget-it option. They blend the C Fund (S&P 500), S Fund (small-cap), I Fund (international), F Fund (bonds), and G Fund (government securities), then automatically shift you toward bonds and G Fund as your target date approaches. That's a reasonable idea for someone who will never look at their TSP again. It is a bad idea for someone with 20-30 years of runway who wants every dollar working as hard as possible.

I'm not against diversification as a concept. I'm against diluting a decades-long compounding engine with international and bond exposure I never asked for, based on a target retirement date some algorithm assigned me.

What Blending Actually Costs You

Here's the part nobody runs the numbers on. Say you're contributing $700 a month to your TSP — a realistic number for a mid-career NCO maxing out what they can. Over 20 years, a pure S&P 500 track record (the C Fund) has historically compounded faster than a blended fund carrying bonds and international drag. Model it at 10% average annual growth versus 8.5% for a diluted blend, and your $8,400-a-year contribution turns into roughly $481,000 at 10% and roughly $406,000 at 8.5%. That gap — nearly $75,000 — isn't a rounding error. It's the price of a default you never chose to opt into.

I'm not throwing out exact historical returns to make a point — those numbers are illustrative, not a promise. But the mechanism is real: every percentage point of drag compounds against you for decades, and bonds and international funds exist specifically to reduce volatility, which also means they reduce upside over a long enough runway.

Why the C Fund Is My Whole Position

I've held the C Fund through 2018, through 2020, through 2022. I never sold. Not once. That's the entire strategy — no timing, no rebalancing into bonds because the news got scary, no glide path deciding for me when I should start playing it safe. Outside the TSP, my brokerage account is 100% VOO and VFIAX, same idea, same discipline. One index, held forever, funded relentlessly.

The G Fund and F Fund have a place — for someone five years from actually needing the money, or someone who cannot stomach a 30% drawdown without doing something stupid. That's not a knock on anyone. But if you're 25, 30, even 40 with two decades left in the market, blending your TSP into bonds this early isn't caution. It's giving up growth you don't need to give up yet.

Boring on Purpose

This is what I mean when I say boring on purpose, relentless by design. I didn't pick the C Fund because it's exciting. I picked it because it's the simplest way to own the entire growth engine of the U.S. economy, and simple is what survives 20 years of deployments, PCS moves, and market crashes that make everyone else panic-sell. Complexity is where good intentions go to die. A blended fund with five moving parts gives you five things to second-guess when the market drops. One fund gives you one job: keep contributing.

I'm not a financial advisor and I'm not going to pretend the C Fund is right for every person reading this. Your risk tolerance, your timeline, your other assets — that's yours to weigh. I'm not a guru handing down rules. I'm a battle buddy telling you what actually built my number, and showing you the math so you can decide for yourself.

Go log into your TSP account today. Look at what fund you're actually in. If it's an L Fund and you're decades from touching this money, ask yourself whether that default was ever actually a decision — or just the box nobody unchecked.