I pay NI but my mother is retirement and earns only a little. Will she have to pay the extra tax?

Anyone of working age earning more than 89 per week pays NI on their earning up to a maximum of 585 per week (595pw from 6 April).

However, there are about 100,000 women who elected between 1948 and 1977 to pay a reduced rate of NI, called the “married women’s reduced rate”.

The rate is currently charged at 3.85% well below the standard rate of employees’ NI, which is currently 10%.

But they will have to pay 4.85% from April - an increase of more than a quarter.

From April, their payments will incur an additional 1% of all earnings above the lower earnings limit threshold, the same as all employees, employers and self-employed workers.

Will top earners pay more?

Unlike previous rises in NI contributions this increase will have a greater impact on the wealthy.

For the first time the government has decreed that the extra penny rise will apply on earnings above the upper earnings threshold (595pw from April).

At the time of the some wealthier individuals could be forgiven for breathing a sigh of relief.

There had been some talk that the upper earnings limit on NI contributions was going to be abolished.

This could have seen annual tax rises for the rich not in the hundreds but the many thousands.

Why was there a year’s delay between the announcement and the tax rise?

At the time of the original announcement the government’s finances were in good shape.

In short, they were bringing in more money than they were spending, even with big expensive projects renewing the NHS in the pipeline.

As a result, the government took the less politically painful and unprecedented step of delaying the tax rise - sweetening the pill a little.

However, since then, many observers believe the government’s finances have taken a sharp turn for the worse.

Tax revenues have been lower than originally forecasted as a result of sluggish economic growth.

And, with the government committed to increase spending on public services, there is a growing fear that a financial “black hole” may be developing.

And if that happens, this April’s NI rise may be the first of many.

Gordon Brown delivers his next budget on 9 April.