Whether salary exchange impacts your parental leave will depend on your company's parental leave policy. If they offer statutory maternity/paternity leave then read on below. If they offer enhanced parental leave, then you should refer to your employee handbook

Maternity leave: Statutory Maternity Pay (SMP) is paid for up to 39 weeks. You get:

Paternity leave: You can choose to take either 1 or 2 weeks. The statutory weekly rate of Paternity Pay is £156.66, or 90% of your average weekly earnings (whichever is lower). For more info see HMRC here

Under salary sacrifice, what counts as your average weekly earnings is the post salary sacrifice amount. Therefore when you are paid 90% of your weekly earnings in the first 6 weeks of maternity leave, the gross amount considered is less. However, due to reduced tax, NI and the fact that you will not be subject to a pension deduction, your overall net pay will be higher. Alongside this, your employer's pension contribution will also be higher than before you switched to salary sacrifice.

Statutory maternity pay takes into account your gross pay which is higher before salary sacrifice. Therefore in the first 6 weeks of maternity leave, the worked example being paid £30,000 would have SMP of £519 per week before salary sacrifice, whereas after salary sacrifice you would have SMP of £499 per week. Over the 6 week period, this would amount to a net pay increase £13.48, with an additional amount of £6.36 paid into your pension.

As a Statutory payment cannot be reduced by a salary sacrifice pension, while in receipt of SMP, the employer will pay the full employee + employer contribution to the pension provider based on your full, pre-SMP salary. The above figures assume this as a total 8% employer contribution.