How long a monthly withdrawal can last

How a withdrawal plan works

A systematic withdrawal plan, often called an SWP, begins with a lump sum in an investment. Each month a fixed amount is sold and paid to you, and the remainder stays invested and keeps earning. People use it to turn savings into a monthly income during retirement, a career break or a period of study.

The arithmetic each month is simple. The balance first earns a month of return. Then the withdrawal comes out. What is left is next month's starting balance. In symbols, new balance equals old balance times one plus the monthly return, minus the withdrawal. Repeat that for as many months as you like, and you can see exactly when, or if, the pile reaches zero.

Two forces work against each other. The return pushes the balance up. The withdrawal pushes it down. If the return earned in a month is larger than the withdrawal, the balance grows. If it is smaller, the balance falls, and the shortfall is taken from principal. A smaller principal then earns less the next month, which makes the next shortfall larger. That feedback is why a withdrawal that looks sustainable at the start can accelerate downward over time.

The SWP calculator shows the balance year by year for the inputs you enter, and the SWP calculator guide explains each field. A withdrawal that runs out tells the same story in a shorter piece, with attention to why the early years matter most.

Test three returns, not one

The first mistake in planning a withdrawal is entering one return and accepting the answer. Returns on investments that can fall in value are uneven, and you cannot know the average in advance. Instead, run the plan at a hopeful return, a moderate one and a poor one.

Here is a pile of ₹50 lakh with ₹40,000 withdrawn each month, using the standard monthly compounding calculation. Each result is the time until the balance reaches zero.

• 12% a year: the balance never runs out. Monthly return on ₹50 lakh is about ₹50,000, which exceeds the withdrawal, so the pile grows.
• 10% a year: the balance never runs out. The first month's return is about ₹41,700, just above ₹40,000, and the pile slowly grows.
• 8% a year: about 22.5 years. After 5 years the balance is about ₹45.1 lakh, and after 10 years about ₹37.8 lakh.
• 6% a year: about 16.4 years. After 5 years the balance is about ₹39.5 lakh, and after 10 years about ₹25.4 lakh.
• 4% a year: about 13.5 years.
• 0% a year: about 10.4 years, which is simply ₹50 lakh divided by ₹40,000 a month.

The pattern is that outcomes diverge sharply near the point where the return roughly equals the withdrawal. Moving from 10% to 8% takes the plan from lasting forever to lasting about 22 years. Moving from 8% to 6% takes six years off the life of the pile. The plan is most sensitive to the return in exactly the range where many people assume they are safe.

The withdrawal rate: a quick sizing check

Before you run a calculator, divide the yearly withdrawal by the pile. ₹40,000 a month is ₹4.8 lakh a year. On ₹50 lakh, that is 9.6%. Compare it with the return you can reasonably expect after costs and tax, over the whole period. If the withdrawal rate is higher than the return, the pile must shrink. If it is far higher, it will shrink quickly.

A lower withdrawal rate gives far more room. Compare four monthly withdrawals from the same ₹50 lakh at a 6% assumed return:

• ₹30,000 a month (7.2% a year): about 29.9 years.
• ₹35,000 a month (8.4% a year): about 20.9 years.
• ₹40,000 a month (9.6% a year): about 16.4 years.
• ₹50,000 a month (12% a year): about 11.6 years.

A ₹10,000 difference in the monthly withdrawal, from ₹40,000 to ₹30,000, adds roughly 13 years. That is a larger effect than a two-point change in the return. If the plan does not last as long as you need, the cleanest lever is usually the amount you take out.

You can also reverse the question. How much can the pile pay each month for a fixed time? For ₹50 lakh and 25 years, a flat withdrawal that exactly empties the pile is about ₹26,400 a month at 4%, ₹32,200 at 6%, ₹38,600 at 8% and ₹45,400 at 10%. For 30 years it is about ₹23,900 at 4%, ₹30,000 at 6% and ₹36,700 at 8%. These are not safe amounts, they are the break-even amounts. Any withdrawal below them leaves something at the end, and any above them leaves nothing.

Why the first years matter most

An average return is not the whole story, because the order of returns matters when money is being taken out. A poor year early in the plan hits a large balance and removes a large amount, while the withdrawal continues. The balance then has less to recover with.

Here is a stylised illustration. Take ₹50 lakh with ₹30,000 withdrawn each month and a ten-year pattern of yearly returns. In the first version the returns arrive in this order: +25%, +12%, +10%, +8%, +6%, +5%, +4%, -5%, -10%, 0%. In the second version the same ten numbers arrive in reverse order: 0%, -10%, -5%, +4%, +5%, +6%, +8%, +10%, +12%, +25%. Both versions have the same average compound return, about 5.1% a year.

• Good years first: the balance is about ₹58.5 lakh after year 1, ₹64.1 lakh after year 3, ₹65.8 lakh after year 5 and ₹44.8 lakh after year 10.
• Poor years first: the balance is about ₹46.4 lakh after year 1, ₹32.9 lakh after year 3, ₹28.4 lakh after year 5 and ₹24.2 lakh after year 10.

Same average, same withdrawal, nearly twice the money left in one version. The poor-start plan never recovers because the strong years arrive when the balance is small. This is why a single calculator run at a steady return can look comfortable and still hide a risk that matters. If you have the choice, keep the early withdrawals modest, or hold a cash reserve so you do not have to sell investments in a bad year. The article on retirement savings after inflation explains how this interacts with rising costs.

Withdrawals that rise with prices

A flat withdrawal loses purchasing power. If prices rise 5% a year, ₹40,000 buys about 61% as much after ten years. Most people need the payment to grow, so a fair test includes a yearly increase.

The effect is large. ₹50 lakh at 8% with a flat ₹30,000 a month never runs out, because the first month's return, about ₹33,300, exceeds the withdrawal. Give the withdrawal a 5% yearly rise and the money lasts about 18.9 years. With a 3% rise, about 24.7 years. At 6% return and a 5% rise, it lasts about 15.6 years instead of about 30 years flat.

Compare ₹40,000 a month from ₹50 lakh at 8%: flat, it lasts about 22.5 years. With a 5% yearly rise it lasts about 13.1 years, and with a 6% rise about 12.3 years. Adding inflation roughly halves the life of the plan. The inflation impact calculator shows what a given payment will buy in future, and the article on how inflation reduces purchasing power shows the effect over decades. The article on real investment return after inflation and tax explains why the return you plan with should be the one after costs.

Seven steps to test your own plan

1. Write down the pile you will start with. Use the amount you will actually invest on the first day, after any tax or exit charge on the sale.
2. Decide the monthly amount you need. Use your real essential and comfort costs, not a round number.
3. Fix the number of years you need it to last. For retirement, plan for a long life. Twenty-five to thirty years is a common test.
4. Compute the withdrawal rate. Divide twelve times the monthly amount by the pile. Anything near or above your expected return needs extra care.
5. Run the SWP calculator at three returns. Use a hopeful one, a moderate one and a poor one such as 4% to 6%.
6. Repeat with a yearly increase. Use 3% to 5% to see what happens when you keep up with prices.
7. Choose the lowest-return result that still reaches your date. If none does, change the amount, the date or the pile, not the assumption.

Worked example: a retirement pile of ₹80 lakh

Kiran is 58 and has ₹80 lakh in a mix of funds. She wants ₹50,000 a month and would like it to last until about age 83, which is 25 years.

Inputs

• Starting pile: ₹80,00,000.
• Monthly withdrawal: ₹50,000, which is ₹6 lakh a year or 7.5% of the pile.
• Time needed: 25 years, which is 300 months.
• Returns to test: 4%, 6% and 8% a year, with and without a 5% yearly increase.

Calculation

Step 1: flat withdrawal. At 8%, the first month's return is about ₹53,300, which exceeds ₹50,000, so the pile lasts indefinitely. At 6% the monthly return is ₹40,000 against a withdrawal of ₹50,000, and the pile lasts about 26.9 years. At 4% it lasts about 19.1 years.

Step 2: balances along the way at 6%. After 5 years about ₹73.0 lakh remains, after 10 years about ₹63.6 lakh, after 20 years about ₹33.8 lakh and after 25 years about ₹10.7 lakh.

Step 3: add a 5% yearly increase. At 8% the pile now lasts about 17.8 years. At 6% it lasts about 14.9 years. At 4% about 12.9 years.

Step 4: size the withdrawal. The highest first-month withdrawal that lasts 25 years while rising 5% a year is about ₹39,400 at 8%, ₹31,400 at 6% and ₹24,500 at 4%.

Result

₹50,000 a month that rises with prices does not last 25 years at any of the three returns. Held flat, it lasts through the period at 6% and 8%, but a flat payment loses a growing share of its value. If Kiran wants a payment that keeps up with prices for 25 years, a starting amount of about ₹31,000 is a sounder plan at a 6% return. She can add other income, such as a pension or part-time work, delay the start, or accept a lower living standard in the later years. Whichever she picks, the calculation shows her the trade before she commits.

A cash reserve to avoid selling at the wrong time

The sequence effect has a practical response. Keep one to two years of withdrawals in a safe, easy-to-reach place, such as a savings account or a short-term deposit, and fund the monthly payments from that reserve during a poor market. Refill it from the invested part when markets are strong.

For Kiran's ₹50,000 a month, two years of payments is ₹12 lakh. That is 15% of her ₹80 lakh. The reserve lowers the expected return on the whole pile a little, because cash earns less. It also reduces the chance that a bad first two years force her to sell growth investments at low prices. A modest reserve is a trade of some return for some stability, and many retirees find it easier to hold their nerve when the monthly payment does not depend on the day's market. The article on how much emergency fund you need covers how to size a buffer.

Costs, tax and the return you really keep

The return you enter should be the return you keep. Fund costs, brokerage, exit loads and tax on gains each reduce it. A fund that earns 8% before costs and tax may leave you with 6.5% to 7% afterwards, depending on the rules where you live. That difference matters because the plan is sensitive near the break-even point.

Two other costs show up in a withdrawal plan. First, each withdrawal is a sale, and a sale may trigger tax on the gain portion. The gain share is larger in the early years of a rising market and smaller later. Second, some funds charge an exit load if you sell units within a set period. Check both in the scheme documents or with a tax adviser, and do not assume the full withdrawal reaches you untouched.

How to read the balance table

When you run the calculator, do not look only at the final number. The yearly balance column tells you much more.

• A balance that rises early and then falls means the return exceeds the withdrawal at first. Later, inflation or a lower return may flip that.
• A balance that falls steadily from year one means you are drawing on principal from the start. Check the slope. A steeper slope means less time.
• A balance that falls faster each year is the signature of a withdrawal that is too large for the return. It is the pattern to avoid.
• The year the balance reaches half is a useful warning. If half the pile is gone and a large part of the plan remains, review the amount.

Using a half-way review date, such as every five years, gives you a chance to lower the withdrawal while there is still something to protect. It is easier to trim a payment by ₹3,000 at year five than to cut it by half at year fifteen.

Common mistakes to avoid

• Running one optimistic return. A plan that only works at the highest return is a hope.
• Ignoring inflation. A flat payment feels adequate in year one and thin in year ten.
• Choosing the withdrawal first and the pile second. Size the withdrawal from the pile, not the other way round.
• Forgetting the sequence of returns. A poor early stretch does more damage than the same poor stretch late in the plan.
• Overlooking tax and exit charges. The amount that reaches you can be lower than the amount sold.
• Planning for too short a life. If the plan stops at 80 and you live to 92, the last years are unfunded.
• Keeping no cash reserve. A forced sale in a downturn locks in the loss.
• Never reviewing. A plan that goes unreviewed for ten years can drift far from its start.

Checklist before you start withdrawing

• Write down the exact amount you will start with after any exit charge or tax.
• List the monthly amount you need, based on real spending.
• Decide how many years the plan must last and add a margin for a long life.
• Compute the yearly withdrawal as a percentage of the pile.
• Run the SWP calculator at a hopeful, a moderate and a poor return.
• Add a yearly increase of 3% to 5% and rerun each case.
• Pick the lowest-return case that still reaches your date and check the payment against it.
• Keep one to two years of withdrawals in a safe, reachable place.
• Check fund costs, exit loads and tax on each sale.
• Note other income, such as a pension or rent, that can reduce the draw.
• Set a review date every year and a deeper check every five years.
• Decide in advance what you will trim if the balance falls faster than planned.
• Keep emergency money separate from the withdrawal pile.

Frequently asked questions