Yes, you can have as many private pensions as you like, each with its own charges; for couples, providers such as ii hold a pension in one name only.
The number of private pensions you may hold is not capped, and a SIPP is no different from any other type. What changes with each extra pot is the paperwork, the charges and the way allowances are shared out. A joint pension is the other half of the question, and the answer interactive investor gives is two pensions, one in each name. Where your own pots, or your partner's, leave the choice unclear, a free phone call-back can be arranged: an FCA-authorised adviser will ring, costing you nothing, once this page's form is received.
Can you have more than one private pension?
Yes. MoneyHelper says you "can have as many pension schemes as you like, but you’ll typically pay charges to each pension provider." It makes the same point about types: you can hold a workplace pension from your employer and a SIPP, "or any number of different pension types". So a personal pension, a stakeholder plan, a SIPP and an old workplace pot can all sit side by side, each with its own provider, statement and charges.
Plenty of people end up here without choosing to: a new job brings a new scheme, an old plan stays where it was, and a personal pension is added later. How the types differ is covered in how the UK pension system works and what a personal pension plan is. Whether a workplace pot counts as private is answered in is a workplace pension a private pension.
How many SIPPs can you have?
MoneyHelper answers this exact question the same way: as many as you like. The practical limit is your own time. Picking your own investments can be complex, so check you have the time and expertise to manage several schemes before opening more than one. Two SIPPs mean two sets of fees, two logins and two sets of investments to keep an eye on. Moving money from one plan into another is covered at how to transfer a pension. What a SIPP is has the basics.
Can you have a joint personal pension with a partner?
Not as one shared plan with interactive investor, which says "you cannot open a joint SIPP account" and that "SIPPs (or any other pension account) can only be opened and held in one person’s name." That is one provider's rule. Whether another provider or scheme works differently is worth putting to an adviser, who can explain it at no cost after the enquiry form here has been sent.
Joint things that do exist in retirement are different products. A joint life annuity keeps paying a partner after the annuitant dies, and pensions and divorce explains what can happen to a pension when a marriage ends.
What couples do instead of a joint pension
One pension each is the route ii points to: you "can each open your own SIPP accounts", so that each person builds a pension and controls the savings in their name, even if the retirement income is later managed together. If only one partner has money to put in, "it is still possible to spread that payment across two SIPP accounts", which gives both of you savings in your own name.
There is a tax angle too. GOV.UK says someone else paying into your pension, a partner for instance, still brings 20% relief if your provider claims it for you (relief at source). If you pay no Income Tax and have no earnings, GOV.UK says your provider can still claim 20% relief on up to £2,880 of contributions a tax year. The detail is in paying into a spouse's pension. Moving existing pension money from one partner to the other is a separate question, answered at transferring a pension to a spouse.
What several pensions mean for tax and charges
The annual allowance is shared across them. GOV.UK says your annual allowance applies to all of your private pensions if you have more than one, and puts it at £60,000 for the current tax year. It can be lower, for example after drawing flexibly from a pension pot or on a high income. Adding a second pension does not give a second allowance. Each provider's statement shows only whether you went over in its own scheme, which is why GOV.UK adds: "If you’re in more than one pension scheme, ask each pension provider for statements." See the annual allowance explained.
Tax relief is capped by earnings rather than by the number of pots: GOV.UK sets the limit at 100% of your annual earnings. Charges tend to add up, because each provider takes its own; pension charges and fees sets out what to look for. The value of any pension invested in funds can fall as well as rise, and you may get back less than you pay in.
Should you keep several pensions or combine them?
Either is allowed. MoneyHelper says you can pick which pensions to combine and leave the rest separate. Before moving a pot it advises checking for special features, guarantees, exit fees or other penalties, and it notes that some schemes accept transfers in only during your first year of joining, or not at all. What your own pots carry is written in their paperwork, and a call-back is the place to have an adviser go through it. Combining pensions covers the options in more depth.
If you are not sure how many pensions you have, the free Pension Tracing Service can give you contact details for a scheme. It cannot confirm that a pension exists or say what one is worth, and a search starts from the old employer or provider name. See finding a lost pension.
Your questions about holding several pensions
Can I have 2 private pensions at once?
Yes. Two, five or more are all allowed, each with its own provider. Each one is likely to carry its own charges, so it is worth knowing what you pay on every pot.
Do I have a SIPP already?
Look for a statement or letter from the provider that names a self-invested personal pension. A workplace pension is not a SIPP unless it says so. If you are unsure where an old pension is held, the tracing route above is the place to start.
Is it fine to hold a workplace pension and a personal one?
Yes. MoneyHelper says a workplace pension and a SIPP can sit together. How the two relate is covered in the workplace pension guide, and auto-enrolment rules explain why a new job can add one.
Does a second pension raise my tax-free limit?
No, the annual allowance covers all your private pensions together, according to GOV.UK, so a second plan does not add a second allowance.
Can my partner and I share one pension?
Not as a joint plan with providers that, like interactive investor, hold pensions in one name only. Each of you can have your own, and one can pay into the other's.
Several pots and a partner can make a tangled picture. An FCA-authorised adviser can take each pot in turn on a call that is free to you, arranged through the short form here.