Key considerations

• You can open a new ISA and fund it on the same day — even on 5 April — Most major platforms (Vanguard, AJ Bell, Hargreaves Lansdown, Moneybox) allow you to open and fund a new ISA online within minutes. As long as your deposit is received before midnight on 5 April, it counts for the 2025/26 allowance. Use bank transfer rather than debit card for larger amounts to avoid daily card limits, and allow an extra business day to be safe — 4 April is your practical last safe day.
• Cash ISA vs Stocks and Shares ISA under deadline pressure: use a Cash ISA if unsure — If you don't have time to research fund selection, a Cash ISA is a perfectly legitimate use of the deadline. You preserve the allowance inside the ISA wrapper, benefit from tax-free interest, and can later transfer (ISA transfer, not withdrawal) to a Stocks and Shares ISA when you've done more research. The 2024 ISA reforms allow flexible transfers between ISA types — you can move from cash to stocks without losing the protected status.
• Stocks and Shares ISA: lump sum vs drip-feed — The evidence from long-term studies is that lump-sum investing beats pound-cost averaging roughly two-thirds of the time. But the ISA deadline makes this moot anyway. You have two choices: invest the lump sum now to secure the allowance, or leave it in a Cash ISA temporarily and drip-feed into a Stocks and Shares ISA over the year. The key rule: use a transfer, not a withdrawal — withdrawing from an ISA means losing the protected status permanently (unless it's a flexible ISA).
• Couples can each use £20,000 — £40,000 combined per household — Each UK adult has their own £20,000 annual ISA allowance. If you and a partner both have spare cash, you can each shelter £20,000 this tax year — £40,000 between you. If one partner doesn't have savings of their own, consider whether gifting them money to use their ISA allowance makes sense — gifts between spouses and civil partners are generally free of CGT and inheritance tax implications.

Frequently asked questions