The Chancellor's policy sees most welfare payments capped at their current level until 2019, rather than rise in line with wages. It is expected to save £3.5bn.
Osborne argued in July that since the financial crisis, while average earnings had increased by 11%, most benefits had risen by 21%.
The government admitted in an impact assessment drawn up last year that some groups of people would be hit significantly harder than others by the freeze, which coincides with the start of the new financial year.
So who'll be hit the hardest?
Around 33% of women will be hit by today's changes, a disproportionately larger number than the 29% of men affected.
This is because around nine in ten lone parents are women, which is the family type most likely to lose out under the scrapped increases in welfare payments like child benefit and child tax credit.
Householders where the head is under 30-year-old are expected to lose the most amount of money as a proportion of their income from today's freeze.
They will lose an average of £624.
The largest ethnicities that will lose out are those who identify as Black, African and Caribbean.
But it is Asian residents who will see the highest notional losses.
While the government has committed to ensure the most vulnerable people in society are not adversely affected, Citizens Advice warns sick and disabled Employment Support Allowance (ESA) claimants will still be hit.
The majority of the benefit is formed by the 'basic rate' of ESA, which will be subject to the freeze, they say.
"This wider effect is significant, given all who receive the benefit have been assessed to have a disability or health condition that limits their ability to find and retain work.
"If those with work-limiting health conditions are classed as vulnerable, there is a failure to apply this principle consistently to those receiving ESA."
Affected benefits that are now frozen:
1. Main rates of Jobseeker's Allowance; Income Support; Employment and Support Allowance (ESA); and Housing Benefit
2. The work-related activity group component of ESA
3. Child Benefit
4. The basic, second adult, lone parent and 30 hour elements of Working Tax Credit and the individual element of Child Tax Credit
5. The corresponding elements of Universal Credit