The state pension is vital for retirees, but many are underpaid without realising and not getting the payments they deserve.
This was shown in April when 74,000 women were told they would get up to £23,000 each after being underpaid their state pension for years.
The errors focus on automatic cash increases for certain married women, widows and over-80s dating back to 1992 with “enhanced” pensions.
Most of this group will have been married when their husband got the full basic state pension, had husbands who hit state pension age after March 2008 or were married and had pensions less than the standard rate for married women.
The total bill to tackle the shortfalls will be about £2.7billion, according to the Department for Work and Pensions (DWP).
Almost 250,000 people have no state pension at all, according to pension firm Lane Clark & Peacock (LCP) last month.
LCP said these “missing pensioners” could not be explained by deferred pensions, gaps in National Insurance payments or by getting other benefits, ruling them out of the state pension.
How much should I be getting?
The full new state pension is £179.60 per week, though the actual amount you get depends on your National Insurance record. It is usually paid every four weeks, in arrears.
To get the full new state pension amount you must have paid 35 years of National Insurance contributions.
Older pensioners can claim the basic state pension of no more than £137.60 a week currently. This is open to men born before 6 April 1951 and women born before 6 April 1953.
What to do if you think your state pension is wrong
You can check how much you are being paid by monitoring your bank account or annual state pension statement.
If you think you might be one of the 74,000 married women short-changed out of your pension, you can use an online tool to find out here..
It was created by Sir Steve Webb, the former pensions minister.
If you think you have not had the correct state pension amount for any other reason, you should contact the Pensions Service arm of the DWP directly.
You can call on 0800 731 0469, but be aware that the lines are only open from 9.30am to 3.30pm Monday to Friday.
Moira O’Neill, head of personal finance at interactive investor, said: “But don’t rely on these forecasting tools completely as state pensions can change, and are likely to change further.
“In fact, future generations can expect some serious watering down of the state pension. It may not be paid until you are 70 or even 75. Or it might be much less than it is now.”
From next January, British expats in Australia, Canada and New Zealand will not be able to count time spent in these countries as part of the qualification for their state pension .
This applies to UK citizens living in the countries since before March 1 2001.
At present, expats in these countries can still get National Insurance credits while abroad, but the rule change will put them in the same group as most other countries. This means the period abroad won’t count towards their retirement pot.
Read More: Thousands underpaid on state pension – how to check if your weekly rate is correct