The requirement is that your work needs to be 'genuine and effective'.

There is no minimum earnings requirement. However, the Home Office has taken it upon themselves to examine your case a bit more closely if your income falls below the NI threshold. You do not fail because you are under some threshold, but they may scrutinise the 'genuineness and effectiveness' a bit more.

The thresholds have been increasing over the years, you can find historical data for previous years in this table: Rates and allowances: National Insurance contributions - GOV.UK.

The relevant threshold is the Primary Threshold, when you start paying NICs, however, you should also be able to work out whether you earned enough by looking at your payslips and P60s, where you will see whether you had NICs taken off your salary or not.

Although some people got PR certification on the basis of working part-time and earning below the NI threshold, we cannot recommend following this criteria for citizenship applications, since the fee is considerably higher than the PR application fee and non refundable.

If you were a low earner and, therefore, perhaps not regarded as a worker, then CSI might not be of benefit, as you may not have enough money to prove you are self-sufficient. Remember that to be a self-sufficient person you must have CSI and sufficient funds to support yourself.

Zero hours contracts

Being on a zero hours’ contract, in itself, is not a problem. What could be a problem is if an employee has very low earnings or if the earnings wildly fluctuate from week to week or month to month. If this is the case, then the application needs to have an explanation of the situation, and some help with this might be a good idea.

Intermittent work and claiming benefits in between jobs

People have obtained PR certification on the basis of intermittent work while studying, the Home Office will assess each case on its own merits. It depends on how intermittent the work was. This is not something easily assessed without knowing the specific circumstances.