Knowing how much to contribute to your 401(k) — and how to capture every dollar of employer match — is one of the highest-return financial decisions you can make.
2025 and 2026 IRS Contribution Limits
| Contribution Type | 2025 Limit | 2026 Limit |
|---|---|---|
| Employee elective deferral | $23,500 | $23,500 |
| Catch-up (age 50–59, 64+) | +$7,500 | +$7,500 |
| Catch-up (age 60–63 only) | +$11,250 | +$11,250 |
| Total with employer match | $70,000 | $70,000 |
Step 1: Calculate Your Contribution as a Percentage
Annual Contribution = Gross Salary × Contribution Percentage
Monthly Contribution = Annual Contribution ÷ 12
Per Paycheck (biweekly) = Annual Contribution ÷ 26
Example: $75,000 salary, contributing 10%:
- Annual: $75,000 × 10% = $7,500
- Monthly: $7,500 ÷ 12 = $625/month
- Per biweekly paycheck: $7,500 ÷ 26 = $288.46
Step 2: Maximise the Employer Match First
The employer match is an immediate 50–100% return on your money — always maximise it before anything else.
Common match structures:
Dollar-for-dollar up to X%:
- "We match 100% of your contributions up to 4% of salary"
- $75,000 salary → contribute at least $3,000 to get $3,000 free
50 cents per dollar up to X%:
- "We match 50% of contributions up to 6% of salary"
- To get the full match: contribute 6% ($4,500) → employer adds $2,250
Vesting schedule: Check whether the employer match is immediately vested or vests over 2–6 years. Leaving before full vesting forfeits unvested matching contributions.
Step 3: Choose Traditional vs Roth 401(k)
| Traditional 401(k) | Roth 401(k) | |
|---|---|---|
| Contribution | Pre-tax | After-tax |
| Growth | Tax-deferred | Tax-free |
| Withdrawals | Taxed as income | Tax-free |
| Best if | You expect lower taxes in retirement | You expect higher taxes in retirement |
Tax savings calculation (Traditional):
Annual Tax Savings = Contribution × Marginal Tax Rate
Example: $7,500 contribution, 22% bracket → $1,650 in taxes saved this year.
Step 4: Calculate the Paycheck Impact
Your net paycheck reduction is less than your gross contribution due to tax savings:
Net Take-Home Reduction = Contribution × (1 − Marginal Tax Rate)
Example: $625/month contribution, 22% tax bracket:
- Net reduction = $625 × (1 − 0.22) = $487.50/month less take-home
You contribute $625 but only feel $487.50 in your paycheck.
Step 5: Project Long-Term Growth
Future Value = P × ((1 + r)^n − 1) ÷ r
Where P = annual contribution, r = annual return rate, n = years.
Example: $7,500/year for 30 years at 7% growth:
- FV = $7,500 × ((1.07)^30 − 1) ÷ 0.07 = $708,453
Include the employer match ($3,000/year in our example):
- Total contributions = $10,500/year → FV = $991,834
Contribution Strategies by Career Stage
Early career (20s–30s): At minimum, contribute enough to capture the full employer match. Roth 401(k) often makes sense at lower tax brackets.
Mid career (30s–40s): Increase to 15% of gross income total (including employer match). Prioritise traditional if in the 24%+ bracket.
Pre-retirement (50+): Use catch-up contributions. Max the account if cash flow allows — the tax break is most valuable at peak earnings years.
The True Cost of Not Capturing the Match
If your employer matches 4% of a $75,000 salary and you contribute only 2%:
- You receive $1,500 in match instead of $3,000
- Over 20 years at 7% return, that missed $1,500/year = $61,500 in lost growth
Leaving employer match on the table is the single most common (and costly) 401(k) mistake.