Costain Group
Assistant Finance Manager

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Costain and Thames Water – Financial Analyst Opportunity
Costain are working with Thames Water on a variety of water and wastewater projects and have fantastic opportunities for individuals to join our growing AMP8 delivery team, working predominantly across the Thames Valley and Thames South regions. There is a mix of projects ranging from smaller capital maintenance to large civil new build schemes.
At Costain, we believe diverse perspectives drive innovation. If you’re passionate about making a positive impact and think you can bring value to our team, we’d love to hear from you—even if you don’t tick every box. Your unique skills and experiences could be exactly what we need.
This is a home-based role with travel to our Camberley, London, and Nottingham offices as required.
RESPONSIBILITIES
Key Responsibilities
- Support the contract teams in managing the financial performance of the contract and accurately reporting and forecasting the results of the contract. This includes supporting the preparation and review of the Contract Leaders’ Report (CLR) to ensure that it adequately reflects the status of the contract, and that the financial performance is being reported in line with Group guidelines and Financial Reporting Standards.
- Contract Accounting - integrity of costs, revenue ledgers, and transaction processing.
- Ensure that all cash book, accounts receivable, accounts payable, and general ledger books of entry and processes are administered in an accurate and timely manner.
- Maintain Framework Balance Sheet reconciliations on a regular basis.
- Responsible for VAT and CIS submission and queries, including registration where necessary, and compliance with current legislation.
- Manage the contract cash flow including deposits and partner distributions.
- Finance point of contact for internal and client audits.
- Ensure timely partner invoicing and dispute resolution.
- Oversee and support the invoice processing team to ensure the accurate processing, verification, and reconciliation of all supplier invoices, using the Costain E1 plant system.
- Maintain accurate records of all hours worked by all directly employed labor by setting up and maintaining appropriate systems and procedures.
- Record and retain accurate staff costs, whilst maintaining consolidated individual information in relation to IT, Company Vehicles, Company Mobile Phones, HO Professional Service staff, training charges, etc.
- Preparing and posting accurate Journals, Accruals, and Prepayments in line with Accounting Policies and accurate cost allocation.
- Assist with the preparation of accounting papers in conjunction with commercial leads for internal and audit review.
Reasons to use Rodeo
I’m in my final year doing Economics and I don’t know whether to apply for grad schemes now or do a masters first. What do you think?
Honest answer — it depends on where you want to end up. A lot of top grad schemes (Big 4, civil service, banking) don’t need a masters. Let’s look at the ones you’d be competitive for now, and we can decide if a masters actually adds anything.
Also worth knowing: most autumn 2026 applications are open now. Timing matters more than you think.
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Grad scheme, placement, apprenticeship? Not sure what you want yet — that's fine. Your agent talks it through with you and turns "I have no idea" into a shortlist.
Graduate Consultant — 2026 Scheme
Why you're a good match
StrongYour economics background and your summer at a regional bank line up with what PwC looks for on the consulting scheme. Applications close in four weeks.
See breakdownIt searches the market for you
Every day your agent scans the market matching roles against what actually matters to you, not just keywords on a CV.
Why you're a good match
You’ve got the grades and the economics background, and your bank internship is exactly the experience this scheme looks for. Apply soon — deadlines close within the month.
Experience fit
Your summer at the bank plus your econometrics coursework map directly to the day-one responsibilities on this scheme — client modelling, market briefings, and deal support.
Only hits
No noise. No "maybe this fits." Just roles with a clear explanation of why they're right — and where to focus when applying.
Knowledge, Skills, and Experience
Essential
- Experience working in a finance department in a similar role.
- Strong written, oral, and analytical skills with attention to detail and an ethical approach to data including respecting the confidential nature of information.
- Advanced understanding of Microsoft, specifically Excel.
- Self-motivate, reliable, and agile individual.
- Honest, resilient, and competent individual with high emotional intelligence.
- Ability to assimilate, understand, analyze, and present data.
- Ability to solve complex problems under pressure in a calm and rational manner whilst always acting with integrity.
- Able to develop and maintain good relationships with internal and external stakeholders of the business at all levels.
Desirable
- Experience with Microsoft Power BI.
- Experience of working with Oracle Enterprise One.
QUALIFICATIONS
Essential
- Degree-level qualification in a relevant field or substantial experience.
Desirable
- Relevant qualification (i.e., Chartered Accounting).
#LI-JA1
Costain helps to improve people’s lives with integrated, leading edge, smart infrastructure solutions across the UK’s energy, water, transportation, and defence markets. We help our clients improve their business performance by increasing capacity, improving customer service, safeguarding security, enhancing resilience, decarbonising, and delivering increased efficiency. Our vision is to be the UK’s leading smart infrastructure solutions company. We will achieve this by focusing on blue-chip clients whose major spending plans are underpinned by strategic national needs, regulatory commitments, legislation, or essential performance requirements. We offer our clients leading edge solutions that are digitally optimized through the following five services which cover the whole lifecycle of their assets: future-shaping strategic consultancy; consultancy and advisory; digital technology solutions; asset optimization, and complex programme delivery. Our culture and values underpin everything we do.


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Costain appreciate the time and effort taken when applying for one of our positions but, due to the high volume of responses, we are unable to provide individual feedback on candidates at the application phase.
We do share individual feedback following an interview.
A Disability Confident employer will generally offer an interview to any applicant that disclose they have a disability and meets the minimum criteria for the job as defined by the employer.
It is important to note that in certain recruitment situations such as high-volume, seasonal, and high-peak times, the employer may wish to limit the overall numbers of interviews offered to both disabled people and non-disabled people.
For more details, please go to the Disability Confident website: https://www.gov.uk/government/collections/disability-confident-campaign
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