This is the amount you are allowed to claim Tax and NI free in childcare vouchers for whatever payroll period it applies to.

For weekly paid it is £55 per week, for monthly paid it is £243 per month. This is the amount that is set by HMRC.

You are allowed to bank the allowance or claim it in the payroll month

You are also allowed to take vouchers over and above your allowance but your employer would declare the excess on the P11D and/or you would declare it on your self assessment form