Big life changes rarely come with a reminder about tax. But getting married or entering a civil partnership, separating, or divorcing can all affect what you pay and what you need to tell HMRC.

This isn’t a full guide to every situation. It’s a checklist of the main points to think about, so nothing important slips through at a time when you have plenty else on your mind.

Update, October 2026: since September 2025, employed people who don’t need to send a tax return for any other reason can pay the High Income Child Benefit Charge through their tax code, instead of registering for Self Assessment. GOV.UK explains how to pay the charge through PAYE. The other rules in this article haven’t changed.

Key points

Tell HMRC if your name or address changes.
Marriage Allowance lets some couples move part of one person’s Personal Allowance to the other, and it must be cancelled if the relationship ends.
Transfers of assets between spouses and civil partners have special Capital Gains Tax rules, which change once you separate.
Child Benefit and the High Income Child Benefit Charge depend on the income of each person in a couple.
Review your will, pensions and any jointly owned property and accounts.

On this page

Changes of name and address
Marriage Allowance
Capital Gains Tax between spouses
Child Benefit
Practical points after a separation
Sources
Talk to us about your tax after a life change

Changes of name and address

If you change your name when you marry or form a civil partnership, or move home after a separation, HMRC needs to know. You can update most details online through your personal tax account. GOV.UK explains how to tell HMRC about a change to your personal details.

If you’re employed, tell your employer as well, so your payroll records match. If you run a business or a company, check that your details with Companies House, your bank and your customers are up to date too.

Marriage Allowance

Marriage Allowance lets you transfer part of your Personal Allowance to your husband, wife or civil partner. It’s aimed at couples where one person earns less than their Personal Allowance and the other pays tax at the basic rate (in Scotland, the starter, basic or intermediate rate). If you’re eligible, it can reduce the tax the higher-earning partner pays. GOV.UK’s Marriage Allowance guide sets out who can claim and how.

If your relationship ends because you divorce, end your civil partnership or legally separate, you must cancel Marriage Allowance. Either of you can cancel. The change may be backdated to the start of the tax year, which could mean one of you has underpaid tax for that year. The details are on GOV.UK’s page on Marriage Allowance if your circumstances change.

Capital Gains Tax between spouses

While you’re married or in a civil partnership and living together, you don’t usually pay Capital Gains Tax on assets you give or sell to each other. The person who receives the asset takes it on at its original cost, so tax may be due when they later sell it. GOV.UK covers this in its guide to Capital Gains Tax on gifts to your spouse or civil partner.

Once you separate, these rules change, and the timing of any transfers can matter. Since 6 April 2023, separating couples can usually transfer assets between them without a gain arising until the end of the third tax year after the tax year in which they stop living together, or until a court grants the divorce or dissolution, if that’s sooner. Transfers made under a formal divorce or separation agreement, or a court order, have no time limit (HMRC Capital Gains Manual). If you’re dividing property, shares or a business as part of a separation, get advice on the tax position before anything is transferred.

Child Benefit

If you or your partner claim Child Benefit and either of you has income over a certain level, the person with the higher income may have to pay back some or all of it through the High Income Child Benefit Charge. The charge looks at each person’s own income, not your joint income, so a new partner moving in, or a separation, can change who is affected.

If the charge applies to you, you may need to register for Self Assessment. And if your circumstances change, it’s worth checking whether you should keep claiming, stop or restart your claim.

Practical points after a separation

Agree how joint bank accounts, other accounts and debts will be handled, and keep a record of what you agree.
Check who is named on the mortgage, the deeds and any rental property, and how rental income will be reported.
If you share a business, agree who will run it, how profits will be shared and what happens to any director’s loan or shareholding.
Review your will, your pension nominations and any life insurance policies.

Gifts between spouses and civil partners are usually exempt from Inheritance Tax while you’re still legally married, even after you separate, but not once the divorce or dissolution is final.

GOV.UK has a general guide to what you need to do when you separate, including links for help with the legal side. For anything to be legally binding, you’ll usually need a solicitor.

Sources

Our main sources are HMRC and GOV.UK:

Talk to us about your tax after a life change

If you’re getting married, separating or going through a divorce, we can look at the tax side with you, including Marriage Allowance, Child Benefit and the timing of any transfers of property or shares. Call us on 020 7164 0225, send us a WhatsApp message or email your tax question to hello@ibandco.co.uk.

You can also read about our Personal Tax Planning service.

First published 9 July 2024. Tax content checked on 9 October 2026. This article reflects the rules at the date it was first published. Where something has changed since, we’ve added an update note. Rules and rates change, so please check with us before acting.

Please note: this article is general information based on our understanding of UK tax rules at the date shown above. It is not advice for your circumstances, and tax rules and rates can change. Please speak to us before acting on it.