Can I enroll in my 401(k) at any time?

It depends on your employer's plan. Many employers now allow enrollment at any time. Others have specific enrollment windows (quarterly, semi-annually, or annually). Some plans have automatic enrollment — you may already be enrolled without realizing it. Check with your HR department or benefits portal to find out your plan's enrollment schedule.

How much money have I lost by not enrolling?

If your employer matches 50% of contributions up to 6% of salary, and you earn $60,000, you've been leaving $1,800/year in free money on the table. Over 5 years, that's $9,000 in missed match alone — plus the investment growth you missed. Over a career, delayed 401(k) enrollment can cost $100,000-$500,000+ in retirement savings.

Can I make up for missed 401(k) contributions?

You can't retroactively contribute for past years, but you can contribute more going forward. The 2025 limit is $23,500 ($31,000 if 50+). Maximize your contributions, especially to capture the full employer match. You can also contribute to an IRA ($7,000 limit) for additional retirement savings. Starting even a few years late is far better than not starting at all.

I Forgot to Enroll in My 401(k) — Can I Still Sign Up?

If you forgot to enroll in your 401(k), contact HR today — you may be able to sign up immediately. Every pay period without enrollment is lost employer matching contributions you can never get back.

What to Do Right Now

Step	Action
1	Log into your benefits portal or contact HR
2	Check if enrollment is open now
3	Enroll and set your contribution rate (at least enough to get full match)
4	Choose your investments (target-date fund if unsure)
5	Check if auto-enrollment already signed you up

The Real Cost of Delayed Enrollment

Years Missed	Salary $50,000	Salary $75,000	Salary $100,000
1 year	$1,500 match + growth	$2,250 match + growth	$3,000 match + growth
3 years	$4,500+	$6,750+	$9,000+
5 years	$7,500+	$11,250+	$15,000+
10 years	$15,000+	$22,500+	$30,000+

Based on 50% match on first 6% of salary. Doesn’t include investment returns on the match, which would make the loss significantly larger.

How Much to Contribute

Priority	Contribution Level
Minimum: get full employer match	Usually 3-6% of salary
Good target	10-15% of salary (including match)
Aggressive catch-up	Max out at $23,500 ($31,000 if 50+)

Common Employer Match Formulas

Match Formula	Your 6% Contribution ($75K Salary)	Free Money
100% match on first 3%	$4,500 + $2,250 match	$2,250/year
50% match on first 6%	$4,500 + $2,250 match	$2,250/year
Dollar-for-dollar on first 6%	$4,500 + $4,500 match	$4,500/year
25% match on first 6%	$4,500 + $1,125 match	$1,125/year

Investment Options If You’re Not Sure What to Pick

Option	Best For	Why
Target-date fund matching your retirement year	Most people	Automatically adjusts allocation as you age
S&P 500 index fund	Comfortable with all-stock	Lowest fees, broad diversification
Balanced fund (60/40)	Moderate risk tolerance	Mix of stocks and bonds
Default investment (if auto-enrolled)	Not sure	Plan’s default is usually a target-date fund

The Bottom Line

Enroll today — even one pay period of missed employer match is money you can never get back. Set your contribution rate to at least capture the full match (usually 3-6% of salary). If you’ve missed years, contribute as aggressively as you can afford. A target-date fund is a perfectly good “set and forget” investment choice if you’re not sure what to pick.