Adding a partner or a child part-way through the policy year is usually allowed, while changing the cover itself, such as the excess or an optional extra, tends to wait for renewal. That is broadly the split in the Bupa, AXA Health, Vitality and Saga wordings, with conditions worth knowing before you ask. If you would like an FCA-authorised broker to check how your own insurer handles the change, requesting their phone call is free; the form on this page collects only contact basics.
Which changes can happen mid-year and which wait for renewal
This table paraphrases each insurer's own document for a policy you already hold; conditions follow in the sections after it. Moving to a different insurer is a separate question, covered under how to change medical insurance.
| Insurer and document | Add a partner or child during the year | Change excess or options |
|---|---|---|
| Bupa By You guide (BINS 14718, © Bupa 2024), page 42 | Dependants can be added at any time | Asked for at the renewal date |
| AXA Health, Personal Health membership handbook, October 2024 (copy hosted on more-health.co.uk), PDF page 32 | Family member or baby can be added at any time | Within 14 days of receiving membership documents, or at renewal |
| Vitality, Membership Guide (VHTCR0002 08/2024, copy hosted on mytribeinsurance.co.uk), pages 35 and 41 | Partner or dependent children may apply at any time in a plan year | You may only apply to change the level of cover at the annual renewal date |
| Aviva, Healthier Solutions policy terms, print reference AV1590050_GEN6842_0326 (check the terms sent with your quote), PDF pages 31 to 33 | Members can be added at any time through Aviva | Contact Aviva, which reviews each member's claims and health first |
| Saga Healthplan Super, policy book dated May 2025, PDF page 31 | Family member can be applied for at any time | May be possible at renewal; call Saga to discuss the options |
WPA's Complete Health brochure (effective 1 October 2026, 07/260728, page 29) says: "Any changes to the policy may only be made at renewal." If you hold WPA cover and want to add someone during the year, ask WPA how that line applies before you assume either way.
Adding a partner or child to Vitality, AXA, Aviva or Saga
Each insurer has its own gate, and joining is not automatic at AXA, Saga or Vitality. AXA says it "can refuse to add a family member to the plan" and will tell the lead member (PDF page 37); Saga's terms say much the same (PDF page 36).
Vitality asks for a form. A partner must share your address and be aged 18 to 79 when the plan or their own cover begins, and children must be 25 or under on theirs (page 41). If Vitality accepts them it issues a revised membership certificate showing their start date and special terms.
AXA wants a phone call (0800 048 1206 in the handbook). It says you can normally add a partner who is married, in a civil partnership or living with you permanently in a similar relationship, plus children of either of you (PDF page 32).
Aviva allows one spouse or partner on a policy, with their children, and members are added by contacting it (PDF pages 31 to 32). Saga asks you to phone and sends forms to complete (PDF page 31).
Bupa: what you can change, and whether you can do it online
The By You guide splits the question in two. Adding dependants, and removing Add-ons, can happen "at any time". Excess and cover options wait: "At your renewal date you can ask us to" add, remove or change an excess, remove Add-ons or change cover options, after which Bupa tells you if the request is possible and whether your price moves (page 42). If you are told Bupa can't change your cover part-way through the year, that renewal-date rule is the one to ask about.
Only the main member can add or remove dependants, even if an authorised signatory manages the rest of the cover (page 43). A dependant is your partner and any child you or your partner are responsible for who is named on your certificate (page 47). However you ask, the guide says no change is valid until it is agreed between the main member (or authorised signatory) and Bupa and confirmed in writing (page 43). How to send the request for your own policy is something the broker who rings you can talk through.
Is the person you add underwritten afresh?
When Vitality accepts someone mid-year, the revised certificate confirms their cover start date and any special terms "including any personal medical exclusions" that may apply to them (page 41). AXA's handbook lists the underwriting styles and says medical history disregarded is normally kept for people continuing cover from a different insurer or a company membership, or for a newborn joining the membership (PDF page 14). Which of these terms an adult partner joining mid-year would get is worth confirming before they are added.
The moratorium is where this bites. Vitality's clause needs two continuous years without treatment, medication or advice for the condition after the cover start date, which it defines as the date each insured person's cover starts, as shown on the membership certificate (pages 30 and 45). Bupa says a dependant's cover start date "may be different" from yours (page 41), and that a dependant joining an existing policy may have an initial year that "may not be a full twelve months" (page 51). Whether an added partner's moratorium clock starts on their own join date, at Bupa or AXA, decides when an old condition could become eligible, so ask before you add anyone. A broker can put that to the insurer for you.
Newborns have their own window
Babies get the most generous terms, with a deadline from the birth: 13 weeks at AXA, three months at Aviva, Saga and Vitality. Aviva asks no premium for three months or until renewal, whichever comes first (PDF page 31), and Saga covers the baby until your next renewal at no extra premium. For Saga to waive its pre-existing conditions exclusion, the mother must have been covered for at least ten months before the birth; Vitality sets the same ten months for a parent before accepting the baby on medical history disregarded terms (Saga PDF page 31; Vitality page 41). The full comparison, including adopted babies and fertility treatment, is on health insurance for a new baby, and Bupa parents can start at adding a child to Bupa.
What happens to the price when someone joins or leaves
Vitality says the premium can change mid-year, including if you "add dependants to your plan, or remove dependants from cover" (page 34). Aviva lists changes it accepts during the policy year, among them removing members, and says they "could result in your premium changing before your renewal date", while with no changes the new premium applies only from renewal (PDF pages 31 and 32). For the changes it takes at your renewal date, Bupa says it will let you know whether your premium will change (page 42). Saga, for changes made during the policy year, only asks for any extra charge if it is over £5 (PDF page 31).
None of these passages sets out a part-year formula, so whether a partner pays pro rata for the months left is for the insurer to quote. Get the figure in writing before you agree; a broker can request it from the insurer when they ring you back, and it costs you nothing to ask.
Changing cover is different. Vitality warns that "any increase in cover or change to your excess may be subject to new acceptance terms" and that you may not be able to change if treatment is planned or a claim is about to start (page 35). A higher excess generally brings a premium down and a lower one generally pushes it up, but each change is priced by the insurer.
Taking someone off the policy
On separation or divorce, Vitality says a partner is no longer eligible as an insured dependant and you must tell it in writing. They may continue on their own plan if they apply within 30 days, otherwise it is a new application with new terms (page 41). If dropping someone pushes the premium under Vitality's minimum, Vitality raises it to the minimum, either when the change is made or at the following renewal (page 40).
Once a child is on a Vitality plan there is no upper age limit for staying on it, but an adult rate applies from the renewal after their 21st birthday, or straight away if they join at 21 or over (page 41). Whether a grown child can move to their own policy on the same terms is worth settling with the insurer before removal.
Adding someone or changing cover: an order to work through
Start with what you want to change. A person can usually be added during the year, so the first check is the newborn window or the insurer's joining rules. A new excess or different options is normally a request for your renewal date, so note that date and raise it shortly before. Moving to another insurer is a switch rather than a change, and the renewal period matters there.
Three questions are worth having ready when the broker calls: which underwriting terms the person you are adding would join on, when their moratorium or exclusions would start, and what the premium would be for the rest of the policy year.
Odd cases people ask about
Can I add my partner to my Vitality health insurance without waiting?
On the guide's wording, yes: a partner may apply at any time during a plan year, by form, if Vitality accepts them (page 41).
What if I miss the newborn deadline?
The newborn terms are tied to an application window, so the baby may then join on different terms. The insurer decides, so act within the window.
Can I change my Bupa cover online?
Adding a dependant can be asked for at any time, while an excess or cover option change is a request for your renewal date, and Bupa writes to confirm any change and the date it starts (By You guide, page 42). If you would rather handle it in your Bupa online account, raise that with the broker who phones you; checking costs nothing.