Savings more than ISA limit

[newhighersalary]

I'm fortunate to have gotten a new job that enables me to potentially save more than the ISA limit (comission based).
Any suggestions on how to use the extra more efficiently?
I'm thinking of overpaying my mortgage. Any other savings account after tax would result in me gaining less, than the interest savings on mortgage (rate is 3.75%).
I did think of investing in a tracker fund - but I'm aiming to overpay at the end of my mortgage fixed term in 3 years. If the value of investments is low at that point , it would be difficult.

Thanks all

Yes i’m aware it’s not the most financially sound option but it’s right for me. I have a pension and some savings. I save and i overpay. Happy with my choices.

I've seen countless examples on MN where people are overpaying into a mortgage that costs 2-3% but they could receive 5% on their savings. You have to factor in your tax situation or put it in a cash ISA but it's a no brainer not to overpay if you're making more interest after tax than you're paying on the mortgage (plus the benefit of compound interest over time).

You're not taking any additional financial risk, the money is still there in your savings account. You also avoid the situation where there's an emergency and you could have used that pot.

This is the reason why gilts (UK Government Bonds) have become so popular.
Older gilts are becoming a key component in tax planning and savings strategy for higher earners.

In a nutshell -
Buy older gilts at a discount - hold them to maturity to receive back their face value (guaranteed by UK Government) - which makes a capital gain - Capital gains are tax-free for Gilts.

https://www.thisismoney.co.uk/money/investing/article-12817487/Try-buying-GILTY-pleasure-beat-taxman.html

Are you a higher rate tax payer and have the £500 limit on income from interest? Interest on savings accounts is less than 5% at the moment so you could have £10k in savings and be under the limit.

Is the extra money a lump sum or building up monthly? If the latter, remember it won't earn a full year's worth of interest, so that will help you stay under the limit too.

3 main options for tax free savings. ISA, Pension and Premium Bonds.