"Our taxes are taken out of our pay and we don't file. We probably pay more than we should"

It could be worth using the HMRC on line service to see if you are paying too much tax, even if you are not required to submit a tax return. You can always delete the figures afterwards. The tax calculation facility is very useful.

The important thing is to check your PAYE code number, because this determines the amount of tax deducted from your salary.