Any cash that you pay into your ISA this tax year counts towards your annual ISA allowance. This is true for payments that you added to your ISA portfolios with InvestEngine, as well as for any payments you made this tax year with your previous ISA provider before transferring to InvestEngine.
ISA transfers will include both this tax year’s payments as well as the balance of your previous year’s ISAs. Only payments made this year count towards your ISA allowance.
The cash balance will remain uninvested only if you are using a DIY Portfolio with the AutoInvest feature turned off.
This feature may be useful if you want to reduce your exposure to the market and employ the PCA (pound-cost averaging) strategy, where you invest only a portion of your total planned investment budget every month.