The life cycle income hypothesis asserts that consumers save and consume based on their optimal consumption pattern over their lifetime, subject to resource constraints. It emphasizes saving during working years to fund consumption in retirement years when income is lower. The hypothesis divides a person's life into three stages - childhood, middle age, and old age - with consumption gradually rising and income peaking in middle age then declining in retirement, resulting in dissaving early and late in life and saving in middle years.

1. Life cycle income hypothesis
BY: AMRINA ABID

2. Introduction
In a series of paper written in 1950 Franco Modigliani and his
collaborators Albert and Richard Brumberg used fisher’s model
consumer behavior to study the consumption function.
This theory emphasizes that the consumer and save out of the total
life income and plan to provide for the retirement.

3. Definiton
Life cycle hypothesis asserts that savings and consumption decisions of household reflect a plan
for an optimal consumption pattern over their lifetime, subject to the constraint of their
resources.
We can also define this hypothesis as:
“the theory of consumption that emphasizes the role of savings and borrowing and
transferring resources from those time in life when income is high to those time when income is
low such as from working years to retirement”.

4. Main theme
This theory of consumption by modgiliani explains the fact that consumption of
a person in a time period(t) depends upon the current income and future
income.
Ct=f(Py,Pt)
Yt= current income
Py = present value of future income
Ct= consumption in a time period

5. Important characteristics
In this theory Modiglianis introduced a new element. This new element is
“ AGE OF CONSUMER UNIT”
According to this theory person’s life divided into three stages

6. Explanation
These stages are childhood, middle age, old age.
Consumption rises gradually, income rises sharply over the early working years peaks and
decline, especially with the retirement.
The pattern of consumption and income is result in dissaving in the early years and late stage of
life cycle.
And in the middle years, income high and consumption is low which results positive saving.

7. Short run consumption function
(SRCF)
SRCF shows a non proportional relationship between consumption and income.
The value of MPC is less than APC.
General form: C=Co+Cy
0
0.5
1
1.5
2
2.5
3
Category 1 Category 2
Series 1 Series 2 Column1

8. Long run consumption function
(LRCF)
LRCF shows a proportional relationship between income and consumption.
The value of APC remains constant and equal to MPC.
The value of APC is less than 1.
0
1
2
3
4
5
6
Category 1 Category 2 Category 3
Chart Title
Series 1 Series 2 Series 3

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