Cash-to-Compounding · Phase 5 of 6
Phase 5: Invest 15% of Gross Income
Phase 5 is Compound Ignition. With cash flow controlled, a reserve in place, cover bought and costly debt gone, 15% of gross income goes to work every month in tax-advantaged accounts.
Finish line
15% of gross income invested every month
Data snapshot
- Year over year
- +14.3%
- 12-month range
- 6,344 – 7,799
The S&P 500 is the benchmark most retirement money tracks through index funds. Its swings are the reason this step is a decades-long commitment rather than a bet on any one year.
What account order gets the most from 15%
Start with the employer match in a workplace plan, because it is an immediate return no market offers. Contribute at least enough to take the full match — leaving it is refusing part of your pay.
Then fund a Roth IRA if you qualify, which gives you tax-free growth and far wider fund choice than most workplace plans. If 15% is still not used up, go back to the workplace plan and raise the contribution until it is.
- Workplace plan up to the full employer match
- Roth IRA to the annual limit, if income allows
- Back to the workplace plan until 15% of gross is invested
- Taxable brokerage only after the tax-advantaged room is used
Why 15% and not 10% or 20%
Fifteen per cent over a full career, invested in broad equity funds, has historically produced a balance that supports something close to pre-retirement living standards alongside Social Security. Ten per cent typically leaves a gap that has to be closed by working longer.
The percentage is of gross income and it excludes the employer match — the match is a bonus, not part of your fifteen. If you start after forty, the honest figure is higher, closer to 20-25%, because there is less time for compounding to do the work.
What to actually invest in
Broad, low-cost index funds covering the whole US market, with international exposure, held for decades. Expense ratios matter more than most people believe: a 1% annual fee removes a large share of a lifetime balance compared with a fund charging 0.05%.
Avoid picking individual shares with retirement money, avoid funds you cannot explain in a sentence, and avoid changing the allocation because of headlines. The plan works because it is boring and automatic.
Do not stop for market falls
Falls are part of the arrangement, not a failure of it. Contributions made during a down market buy more shares, which is why steady investors finish ahead of people who wait for calm.
The behaviour that destroys retirement outcomes is selling after a drop and returning after a recovery. Automate contributions so the decision is not made monthly.
Phase 5 runs at the same time as 5 and 6
Unlike the earlier steps, this one does not finish. Fifteen per cent keeps going while you save for college in Phase 6 and overpay the mortgage in Phase 6.
The order matters if money is tight: retirement first, then college, then extra mortgage payments. Children can borrow for university; nobody lends for retirement.
Project your retirement balance
Projected balance in 30 years
$1,137,807
- Total contributed
- $266,000
- Investment growth
- $871,807
- Annual income at 4%
- $45,512
- Monthly income at 4%
- $3,793
Year-by-year projection
Contributions and compound growth split out for every year, so you can see when growth starts outpacing what you put in.
| Age | Contributions | Growth | End balance |
|---|---|---|---|
| Age 36 | $57,200 | $3,850 | $61,050 |
| Age 37 | $64,400 | $8,499 | $72,899 |
| Age 38 | $71,600 | $14,004 | $85,604 |
| Age 39 | $78,800 | $20,428 | $99,228 |
| Age 40 | $86,000 | $27,837 | $113,837 |
| Age 41 | $93,200 | $36,302 | $129,502 |
| Age 42 | $100,400 | $45,899 | $146,299 |
| Age 43 | $107,600 | $56,711 | $164,311 |
| Age 44 | $114,800 | $68,824 | $183,624 |
| Age 45 | $122,000 | $82,334 | $204,334 |
| Age 46 | $129,200 | $97,341 | $226,541 |
| Age 47 | $136,400 | $113,953 | $250,353 |
| Age 48 | $143,600 | $132,287 | $275,887 |
| Age 49 | $150,800 | $152,466 | $303,266 |
| Age 50 | $158,000 | $174,625 | $332,625 |
| Age 51 | $165,200 | $198,906 | $364,106 |
| Age 52 | $172,400 | $225,463 | $397,863 |
| Age 53 | $179,600 | $254,460 | $434,060 |
| Age 54 | $186,800 | $286,073 | $472,873 |
| Age 55 | $194,000 | $320,493 | $514,493 |
| Age 56 | $201,200 | $357,921 | $559,121 |
| Age 57 | $208,400 | $398,576 | $606,976 |
| Age 58 | $215,600 | $442,690 | $658,290 |
| Age 59 | $222,800 | $490,513 | $713,313 |
| Age 60 | $230,000 | $542,314 | $772,314 |
| Age 61 | $237,200 | $598,380 | $835,580 |
| Age 62 | $244,400 | $659,020 | $903,420 |
| Age 63 | $251,600 | $724,564 | $976,164 |
| Age 64 | $258,800 | $795,366 | $1,054,166 |
| Age 65 | $266,000 | $871,807 | $1,137,807 |
Data sourced from
- IRS annual inflation adjustments (Rev. Proc. 2025-32)
This retirement calculator projects your retirement balance from current savings, contributions and expected return, then converts that balance into sustainable annual income.
The projection compounds monthly, which is how workplace plans actually credit growth.
Frequently asked questions
More calculators
How to complete Phase 5
- 1Contribute enough to the workplace plan to get the full employer match
- 2Open and fund a Roth IRA if your income allows it
- 3Raise the workplace contribution until total contributions hit 15% of gross
- 4Choose broad low-cost index funds and leave the allocation alone
- 5Increase the contribution with every pay rise instead of the spending
Frequently asked questions
Get a plan built around your numbers
Match with a vetted fiduciary financial advisor near you and pressure-test where you are in the six phases.
Talk to a financial advisorEditorial disclosure — Some companies listed here are commercial brands. We select them editorially from public regulatory data and are never paid for placement or ranking. Read our full disclosure.
Data sources & methodology
- Federal Reserve, G.19 Consumer Credit — Every figure quoted on this page comes from this release. View the source data
- Bureau of Economic Analysis, personal saving rate — Every figure quoted on this page comes from this release. View the source data
- Bureau of Labor Statistics, Consumer Price Index — Every figure quoted on this page comes from this release. View the source data
- Federal Reserve, Survey of Consumer Finances — Every figure quoted on this page comes from this release. View the source data
Figures on this page are quoted from the federal releases listed here and refreshed automatically. Where a number is illustrative rather than published — for example a worked example on a $60,000 income — it is described as an example in the text.
Think Bigger Today aggregates data from 4 federal and public sources. Our cross-referenced indices are calculated in-house and are not published anywhere else.