Dates for your financial diary for Q3 2025.
It’s an odd time of year. With people everywhere going on or returning from holidays, it may seem like the world stops and restarts again during Q3.
But there’s still a lot to be aware of when it comes to financial dates for your diary.
Luckily, the experts at Rosemary Bookkeeping are here to keep you on track.
In this blog post, we have compiled a list of dates and guidance on the essential bookkeeping dates and deadlines for Q3 2025.
July 2025
There are a few key deadlines to be aware of in July, particularly regarding employee benefits, including the all-important NIC and self-assessment payments.
- 6th July 2025: All employers must submit forms for P11D and P11D(b) declaring any employee perks and benefits to HMRC (and provide copies for employees). This might include private healthcare, company cars, and gym memberships, for example.
- 19th July 2025: Pay National Insurance Contributions on benefits for Class 1A NIC Payment
- 31st July 2025: Deadline to make the second advance payment for Self-Assessment taxes for 2024/25
August 2025
There’s a bit of a break in August, without many deadlines to concern yourself with, which might make it the best month to take your holiday!
- 3rd August 2025: If you have employees with a company car, this is the deadline for submitting a P46 for the quarter ending 5th You can either use the online service or fill in the postal form and return it to HMRC that way
September 2025
September marks the deadline for your VAT returns, which are essential and must be done before the month’s end. While not a deadline, in mid-September, we can also expect the Office for National Statistics (ONS) to announce UK wage growth figures. This can be useful to be aware of, as it will impact state pension increases.
- 30th September 2025: Q3 deadline for VAT returns (covering July-September 2025).
Need help with your bookkeeping?
With much more to keep track of throughout the year, you can take some of the stress out of your business operations by leaving your bookkeeping to the professionals.
Entrusting your bookkeeping to Rosemary means:
- We keep track of your deadlines for you
- We know when your Tax return needs to be filed by
- We can keep track of your CIS payments
To learn more about our services and how Rosemary Bookkeeping can help you, call 0345 862 0072 or find your nearest Rosemary Bookkeeper today.




