Class 3 National Insurance Contributions (NICs) are a voluntary contribution paid by those wishing to fill gaps in their NICs contribution record and can be used by taxpayers who have not made sufficient compulsory contributions or are not liable to pay any other class of National Insurance contributions.Essentially, Class 3 contributions can be used to secure certain state benefits, and more importantly, entitlement to a full State Pension. The form (CA5603) to pay voluntary Class 3 NICs has recently been updated.It may be worth paying Class 3 NICs if, for example, you are close to State Pension age and don’t have enough qualifying years to get the full State Pension or if you are self-employed and don’t have to pay Class 2 contributions because you have low profits or live outside the UK, but you want to qualify for benefits.You can pay voluntary Class 3 National Insurance contributions if you are:over 16 not working not liable to pay Class 1 and/or Class 2 National Insurance contributions as a self-employed persona woman who revokes her married woman’s or widow’s reduced rate election part way through a tax yeara self-employed person who has profits below the Small Profits Threshold or was previously exempt from paying Class 2 National Insurance contributions.Class 3 NICs are usually paid by monthly direct debit. It is also possible to pay quarterly and there are special arrangements for people who are abroad or are going abroad. For 2018-19, Class 3 NICs are payable at £14.65 per week, so a full year’s worth of contributions costs £761.80. Before paying Class 3 NICs, it is important to check if it is beneficial to do so.