Many people will be in this situation. After the crash of 2008, we had fourteen years of record low interest rates where savers had minimal returns on their savings. Rates started rising again towards the end of 2022 due to the cost of living crisis. Fixed-rate term investments usually offer the best return so many people investing for 12 months would have received a decent amount of interest in late 2023 and beyond.
You query seems to hinge on what you said later, not in the opening post:
… my dh needs to know what we had from the Nationwide bond in 23 to 24 which was changed from Virgin to them in the Spring of that year.
Spring of 2023?
Bonds pay interest either monthly, annually or longer. The precise date of investment and whether you opted for monthly or annual income would determine which tax year interest falls into. If you opened the account on or after 6 April 2023 and opted for annual interest then it would normally be paid on the one year anniversary which would be on or after 6 April 2024. That would put it into tax year 2024-25 so any tax wouldn't need to be paid until 31 January 2026.
This might explain why you haven’t had a Statement of Interest. If interest was paid in 2023-24, I would be very surprised if Nationwide hadn’t already sent you a statement.
I understand what you are saying about sharing everything but you have to make sure that you are both getting all the tax free allowances to which you are both entitled.
You are both entitled to a tax-free Personal Allowance of £12,570 and a Personal Savings Allowance of £1000 (higher rate taxpayers £500). Also, If someone has income (other than from savings) which is less than £17,250, they are also entitled to a starting rate for savings of up to £5000.
This link again explains how this works.
www.gov.uk/apply-tax-free-interest-on-savings
If one spouse does not need of all their tax-free Personal Allowance, they can transfer up to £1,260 of it to the other. This is called Marriage Allowance.
Example: say one spouse has pension income of £20,000 and the other has pension income of £10,000. They also have interest of £4,000 on a joint account - £2,000 each.
The spouse with the pension income of £10,000 would not have to pay tax on their pension or their share of the interest and could transfer £1,260 Marriage Allowance to their spouse.
If they didn’t and HMRC assessed all of the interest on the spouse with the higher income, they would pay £652 too much tax - 20% on the £2,000 that is the income of the other spouse and 20% on the £1,260 tax-free Personal Allowance (Marriage Allowance) that could have been transferred
I hope that makes sense.
You have taken the first step of writing to HMRC about the joint account. Now you need to figure out what your own tax liability is, if any, and pay it before the deadline of 31 January 2025.
www.gov.uk/self-assessment-tax-returns/deadlines