Bookkeeping checklist for clients

As a bookkeeper, part of your job description is keeping track of important accounting-related dates and deadlines that concern your clients. Since your clients might have a limited understanding of how taxes, accounting, and other financial management work, they may rely on you to keep them informed, so they don’t miss any deadlines.

This guide includes bookkeeping checklists for clients for the following areas:

  • Steps to cover when onboarding a new bookkeeping client 
  • Important tax dates and deadlines that concern small businesses
  • The penalties for missing some of these deadlines

Whether you’re just starting out as a bookkeeper or have been active for a while, Countingup is the perfect tool to help you manage your bookkeeping clients effectively.

Bookkeeping checklist for onboarding new clients

Let’s start at the beginning of your client relationship and look at a few steps you should take to get your collaboration off to a smooth start. You’ll want to tick the following boxes:

Sales summary 

It’s always good to set expectations early and summarise what signing with you will mean for the client. Clarify why your client came to you in the first place and what services they were specifically looking for. Use this information to make sure your proposal and work plan meet their needs.

Get to know their business

Another key part of onboarding a new client is to familiarise yourself with their business. Spend some time learning their industry and daily operations to gain more insight into what they do. Understanding exactly how your client’s business works and help you identify areas or services you could upsell to them later on.

Signing the contracts

Once you’ve set expectations and gotten to know your client’s business, it’s time to sign the contracts. When sending the contract to your client, be sure to include the proposal outlining the services you’ll deliver. This will ensure there is no confusion about what is or isn’t included in your fees and service. 

Create the work plan

Compile and share a summary of the project, services and hours you’ll complete for your client. You could use a Gantt chart to organise your work for the client since you can include an individual responsible for each task (such as you and your client) and plot a timeline that everyone can refer to.

Follow up with the client

Set a schedule for checking in with your client, either face to face, via phone, email or a mix of all three. Ask which method the client prefers and if they want a high level of visibility and involvement or if they want you to manage the bookkeeping without needing to be present. Then make a plan for how you’ll stay in touch.

Bookkeeping checklist for clients: tax dates and deadlines

Missing a tax deadline can cost your client a lot of money, so make sure you keep them informed. You might already have a good idea of these important dates, but here’s a list to refresh your memory:


1st – Corporation Tax payment deadline

This is if a client’s limited company’s year-end is 31st March, and they’ll have to pay a penalty if they miss the deadline.

How much the penalty for late Corporation Tax payments lands on is calculated by applying a percentage to the amount of tax that your client owes, which depends on where the error was careless, deliberate, or deliberate and concealed.

If you or your client take action before HMRC does and tell them about the error, it could lower the penalty, so don’t dawdle if a deadline is missed.

31st – Self Assessment tax return deadline

Missing this deadline for the Self Assessment means your client will have to pay a £100 penalty if their tax return is up to three months late. The later HMRC receives the tax return, the higher the fine. Your clients can appeal the penalty if they have a reasonable excuse, but their bookkeeper not sending it on time doesn’t count.

31st – First payment on account deadline

The first late payment penalty is 5% of any tax unpaid after 30 days. If the balance payment is still unpaid after those 30 days, HMRC will add another 5% to the total sum of the tax unpaid plus the first 5%. The same thing happens again after five months and 11 months.


7th – The previous year’s last quarterly VAT return filing deadline

Clients may enter a 12-month ‘surcharge period’ if they default and pay a percentage of the VAT outstanding on the due date for the accounting period. The surcharge rate increases every time they default again in a surcharge period. You can access more details on VAT surcharges and penalties here.


6th – New tax year

The Chancellor’s updates to any tax rates, wage rates and minimum pension contributions come into effect. Clients need to know about this date and what the new changes are. Make sure you keep them informed.

19th – Year-end payroll forms deadline

If your client has employees, these all need to be filed, and the PAYE paid. How much clients have to pay depends on how many employees they have, as listed below:

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If you want more information about these penalties to share with your client, you can find it here.


7th – This year’s first quarterly VAT return filing deadline

The penalty can be a surcharge period or penalty. Find out more details here.


31st – Second payment on account deadline

The first late payment penalty is 5% of any tax unpaid after 30 days, the same as for the first payment on account in February. 


7th – This year’s second quarterly VAT filing deadline

The penalty for missing the deadline is a potential surcharge period or penalty.


7th – This year’s third quarterly VAT return filing deadline

Penalty: same as above.


31st – Deadline for filing company annual accounts 

If the end year of your client’s company is 31st March. The payment deadline is January 1st (the day after). The penalty for late filing is as follows:

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Clients will automatically receive a penalty notice if your accounts are filed after the deadline, and they could blame you for missing it. 

Save time on sole trader clients with Countingup

You can save your practice time on manual admin and help your clients keep organised records with Countingup’s free accounting software. It’s built specifically to help you manage your self-employed and sole trader clients.

The unique business current account and accounting app automates time-consuming bookkeeping admin for your clients so they can focus on running their business—and send you accurate, structured data to work from. 

Countingup’s accounting software is MTD-compatible and full of features for you to efficiently review and manage client accounts with direct access to their real-time organised data. Find out more here.


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