Buying and selling at the same time: how the mortgage process works

Buying and selling at the same time: what to expect

Many home movers aim to sell their current property and buy their next one without a long gap in between. In practice, this usually means coordinating two transactions at once—and often, becoming part of a chain.

The key to keeping things on track is understanding the different ways a move can be structured, how your mortgage may need to change, and where delays typically occur.

Three common ways to time your move

1) Sell first, then buy

With this approach, you market and complete the sale of your current home before purchasing your next one.

Why people choose it

It can reduce the pressure of being dependent on other sales in the chain.
You may avoid some chain complexity on the buying side.

What to plan for

You’ll need somewhere to live between completion dates (rent, family, or temporary arrangements).
You may end up moving twice, which can add cost and disruption.
Your mortgage transition may be less straightforward if you need to redeem or change arrangements before your next purchase.

2) Buy first, then sell

This is less common, but it can work when you need to secure your next home quickly.

How it’s often funded

Some borrowers use additional borrowing arrangements to bridge the gap between buying and selling.

What to plan for

You may be managing two mortgage payments for a period.
Lenders will typically want confidence that you can afford the overall cost of the move.
You’ll need to consider how this affects your deposit and cashflow.

3) Sell and buy at the same time (the chain approach)

This is the most typical scenario for people who want to move directly from one home to the next. It often involves exchanging contracts on both transactions around the same time.

Why it can be attractive

You may be able to avoid temporary accommodation.
You may be able to use sale proceeds as your deposit for the next purchase.
If timing aligns, you can move in without a long wait.

What makes it challenging

You become reliant on other buyers and sellers completing their parts of the chain.
If someone down the chain delays or withdraws, it can affect your completion date.
Your negotiating position can be more constrained because your purchase is linked to your sale.

Your mortgage options when you’re buying and selling together

When you’re moving home, your mortgage plan needs to match the structure of your move. Two common routes are porting your existing deal or remortgaging for the new property.

Porting your mortgage

What it means

Porting is when you transfer (or “carry over”) your existing mortgage deal to your new home.

When it may suit

It can be relevant when you’re moving to a property with a similar value to your current one.

What to consider

Porting isn’t available in every scenario and not all lenders offer it.
Your new mortgage amount, property type, and affordability assessment can still affect what’s possible.

Remortgaging for the new purchase

What it means

Remortgaging is taking out a new mortgage arrangement for the property you’re buying.

Why it’s common

It can be suitable if you’re upsizing, downsizing, or simply want to compare options across the market.

What to consider

If you change your mortgage before the end of your current deal, you may need to account for early repayment charges (where applicable).
Your new mortgage will be assessed based on the new property and your circumstances at the time.

The role of equity, deposits, and loan-to-value

In many cases, you can buy your next home if your sale proceeds cover the mortgage balance and contribute towards your deposit.

If your current property sells for less than expected, or if you’re dealing with a higher loan-to-value position, you may need to adjust your plan—such as changing the property you buy, increasing the deposit, or reviewing the mortgage structure.

How to reduce the risk of delays in a chain

When you’re buying and selling at the same time, the goal is to keep communication flowing and make it easier for everyone involved to meet deadlines.

1) Treat your move like a coordinated project

A chain is only as strong as its weakest link. Build a clear timeline for:

when you expect to exchange
when you’re aiming for completion
key document deadlines

2) Keep your mortgage process moving alongside the legal process

Mortgage steps often need to happen in parallel with conveyancing. If you leave mortgage tasks until late in the process, you can create avoidable bottlenecks.

3) Be ready for document requests quickly

Mortgage applications and property purchases can involve multiple rounds of information. Having key documents organised early can help reduce turnaround times.

4) Plan for insurance timing

Buildings insurance is typically required from exchange of contracts. If you’re insuring two properties around the same time, it helps to understand what cover is needed and when it starts.

5) Consider completion day realities

Completion can be affected by banking and office schedules. If you’re trying to align two transactions, choosing a completion window that gives everyone enough time to process paperwork can reduce the chance of last-minute issues.

Practical tips for a smoother move

Communicate clearly with everyone involved

Regular updates with your solicitor, estate agent, and mortgage adviser can prevent misunderstandings and help you respond quickly if anything changes.

Stay flexible on dates where possible

Even small shifts in completion dates can have knock-on effects. Being prepared to adjust can help the chain keep moving.

Keep your paperwork in one place

Create a dedicated folder (digital and/or physical) for:

identity and address evidence
property-related documents
any information needed for the mortgage application

Get organised early, but don’t overcommit

It’s sensible to start planning your move in advance, but avoid locking into irreversible steps until you’re confident the sale is progressing.

Choosing the right approach for your situation

There isn’t a single “best” way to buy and sell at the same time. The right strategy depends on factors such as:

how quickly you need to move
whether you can manage temporary accommodation
your mortgage deal structure (and whether porting is relevant)
how much risk you’re comfortable with in a chain
your cashflow and deposit position

A well-planned mortgage route and a realistic timeline can make the difference between a move that feels controlled and one that becomes stressful.

Summary

Buying and selling at the same time usually means coordinating two transactions and often working within a chain. Understanding the three main move strategies, choosing between porting and remortgaging, and staying organised with documents and insurance can help you manage risk and keep your move on track.