The state pension rises by up to £343 a year from April 6, but not everyone gets the extra cash.
The amount paid depends on your age, gender and employment history.
The rules are even more complicated for expats who may have a frozen pension package due to where they live.
For people who retired on or after April 6, 2016, the new state pension applies, paying £175.20 a week (£9,110.40 a year) providing they have enough qualifying years to claim the full amount.
For a full claim, you need 35 years of full national insurance contributions or credit, if you were looking after children, a carer or unable to work.
Frozen state pension
Providing you have 10 qualifying years, you can claim the new state pension, but only receive a pro rata payment.
Someone with 10 years receives £50.05 a week (£2,602.97 a year). The payment rises pro rata for each qualifying year over 10 years until the full amount is reached.
For people retiring before April 6, 2016, the basic state pension is paid.
This rises to £134.25 a week (£6,981 a year) on April 6.
Expats with a frozen state pension do not pick up the cost-of-living rise, but remain on the rate when their state pension was first paid unless they live in a country with a reciprocal social welfare agreement with the UK.
Where cost of living increases are paid
During the Brexit transition period, this agreement includes all countries in the European Economic Area (EEA) plus:
- Isle of Man
- Jersey and Guernsey
- New Zealand
- North Macedonia
- South Korea
Expats can get a state pension forecast detailing how much they are likely to get and when online from the UK government web site.
A Government Gateway account is needed to access the calculator.
The few pensioners who claim the Adult Dependency Increase (ADI) alongside the state pension will lose up to £70 a week when the payment is scrapped on April 6. The money was available to pensioners with a financially dependent spouse.
Some pensioners can replace the cash by claiming pension credit or universal credit.