Equal pay law allows you to claim loss of earnings and interest up to a maximum six years past - or five in Scotland.
If we can't negotiate proper compensation with employers, we will have to ask an employment tribunal to award it.
As with all legal proceedings, that involves strict procedures and time limits - and claims can and will fail if these are not met.
And the rules on time limits are very complicated and it is easy to slip up.
You need to claim within a fixed time of leaving the job you were discriminated against in.
Normally, that means when you leave employment, but it can also mean a change of job with the same employer or having your job transferred to a new employer.
In general, you must lodge a written grievance with your employer or former employer within six months of the date of leaving or changing jobs.
You must then wait at least 28 days before lodging a claim with a tribunal Ð but it must be lodged no more than nine months minus one day after leaving the job or changing employer.
The key thing is get help from the union as soon as possible.
Download an enquiry form (PDF format)
Should I worry about the time limits?
Are you still doing the same job as when the discrimination took place? Then the clock is not ticking: you can pursue an equal pay claim at any time - but the later you leave it to claim, the more chance there is that you may miss out on compensation for some past inequality as the tribunal can only award back pay for six years - or five Scotland.
Have you retired in the last six months, or are you planning to retire?
You must pursue a grievance within six months and lodge a claim within nine months, less a day, of retiring.
Have you been promoted or changed to a different job with the same employer?
The time limits could be measured from the change, so you should still pursue a grievance within six months and claim within nine months Ð or risk losing compensation for losses before the change. In some cases, a job change won't trigger a time limit but the only safe course is to assume that time has started to run. If in doubt, consult your union rep.
Have there been significant changes to your job, in, say, its responsibilities or the work you are required to do?
A significant change may also start time running. Again, if in doubt, consult your union rep.
Is your job the same, but your employer has changed through privatisation or transfer?
The time limits are measured from the date of the transfer: pursue a grievance with your old employer within six months and lodge a claim within nine months.
Have you had some compensation already and signed a "COT3" or Compromise Agreement?
Your claim up to the date in your settlement agreement has been concluded and can't be reopened. But you may have a claim for losses after the date of the settlement Ð the rules above will apply to that claim.
If you think you are out of time, contact the union immediately. We will do everything we can to help and may still be able to get some compensation for you.
More information on time limits, and extra copies of the enquiry form are available from UNISONdirect on 0845 355 0845. Textphone 0800 0 967 968, or email direct@unison.co.uk. Lines are open from Monday to Saturday 6am-midnight and on Saturday from 9am-4pm.
UNISON negotiating strategy and guidance for local UNISON negotiators: Update
Equal pay, privatisation and procurement
Getting Equal
