The two-tier scheme applies to men born before 6 April 1951 and women born before 6 April 1953.
You will have already claimed your basic state pension unless you delayed (deferred) your state pension.
The two tiers are made up of the basic state pension and the additional state pension.
Tier 1 – the basic state pension
The basic state pension is based on the number of qualifying years you’ve paid, or been credited with, enough National Insurance contributions to make that year qualify towards your basic state pension. You will get the full the basic state pension of £169.50 a week if you paid or were credited with 30 years of National Insurance contributions. You may need more years of National Insurance contributions if you are a man born before 1945 or a woman born before 1950. Your basic state pension will be less if you have fewer than the full number of qualifying years of National Insurance.
Tier 2 – the additional state pension
On top of the basic state pension, you might also get an additional state pension. The amount will depend on how many years you paid National Insurance for, your earnings, whether you’ve contracted out of the scheme and whether you topped up your basic state pension. If you contracted out of the additional state pension scheme at any point, you won’t qualify for the additional state pension for the period you contracted out. This is because the National Insurance contributions that you would have paid into the additional state pension will have gone into your company scheme or personal pension instead.
You can find out more about the state pension at GOV.UK and MoneyHelper.