The verdict in three sentences
A custom client portal for an accounting practice costs 30,000 to 70,000 GBP in London in 2026, with document upload, OCR extraction and automated reminders, plus 6,000 to 10,000 GBP for a connector to Xero, QuickBooks or IRIS. A SaaS portal at 8 to 15 GBP per client per month remains the benchmark you must beat. For a 350-client practice losing 6 hours a week to chasing, custom pays back in 2 to 3 years only if your workflows genuinely differ from what off-the-shelf tools offer.
Custom or SaaS portal: the numbers
The first question is not technical: what does your current way of collecting documents cost? Between email, WhatsApp, USB sticks and shoeboxes, a staff member spends about 1 hour a week per 60 clients chasing and filing. Here are realistic 2026 options (order of magnitude).
| Option | Upfront cost | Recurring cost | Customization | Data |
|---|---|---|---|---|
| Portal bundled with practice software | 0 to 1,500 GBP | 4 to 8 GBP per client/month | Low | Vendor |
| Specialist SaaS portal | 1,000 to 3,000 GBP | 8 to 15 GBP per client/month | Medium | Vendor |
| Simple custom portal | 30,000 to 40,000 GBP | 200 GBP/month UK hosting | High | Practice |
| Advanced custom portal (OCR, reminders, e-signature) | 45,000 to 70,000 GBP | 250 to 450 GBP/month | Full | Practice |
| Xero, QuickBooks or IRIS connector | 6,000 to 10,000 GBP | included in support | Specific | Practice |
| Support and maintenance retainer | n/a | 700 to 1,500 GBP/month | n/a | n/a |
For 350 clients, a SaaS at 12 GBP per client costs 4,200 GBP a month, so 50,400 GBP a year and 151,200 GBP over three years. An advanced custom build at 55,000 GBP plus 450 GBP a month comes to 71,200 GBP over three years. The gap widens as client count grows.
The modules that actually save time
Not every module has the same return. Uploading alone solves nothing if the client does not know what you need. Targeted reminders are what free up time.
| Module | Budget | Estimated weekly saving | Priority |
|---|---|---|---|
| Drag-and-drop and mobile photo upload | 6,000 to 10,000 GBP | 1 h | Essential |
| OCR (date, amount, VAT, supplier) | 6,000 to 9,000 GBP | 1.5 h | High |
| Missing-documents list per client and automated reminders | 5,000 to 8,000 GBP | 2.5 h | Essential |
| Secure messaging and history | 4,000 to 6,000 GBP | 0.5 h | Medium |
| E-signature for engagement letters | 2,500 to 4,000 GBP | 0.5 h | Medium |
| Multi-factor authentication and UK GDPR access log | 3,000 to 5,000 GBP | n/a | Mandatory |
UK hosting at around 200 GBP a month meets client and ICAEW expectations on confidentiality. UK GDPR requires a record of processing, defined retention periods and breach notification to the ICO within 72 hours. Making Tax Digital for Income Tax, phased in from April 2026, adds pressure for clean digital records.
Mini case study
Oliver, partner at a 350-client accounting practice in Islington, measures 6 hours of chasing per week across three staff. He orders an advanced portal at 48,000 GBP and a Xero connector at 8,000 GBP, so 56,000 GBP plus 450 GBP a month. Chasing drops to 1.5 hours a week, saving 4.5 hours, about 200 hours over 45 weeks. At 120 GBP per billable hour, that is 24,000 GBP a year. Adding 2 hours a week of data entry avoided by OCR (90 hours, 10,800 GBP), the yearly gain reaches 34,800 GBP, minus 5,400 GBP of running costs: 29,400 GBP net. Payback: about 23 months, against a SaaS bill of 50,400 GBP every year.
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FAQ
How much does a client portal for an accounting firm cost in London in 2026?
Plan 30,000 to 70,000 GBP depending on modules, plus 6,000 to 10,000 GBP for a connector to your practice software. UK hosting runs around 200 GBP a month.
At what client count does custom make sense?
Below 150 clients, a SaaS portal at 8 to 15 GBP per client per month is cheaper. Above 300 clients, custom becomes cheaper from year three onward.
Is OCR reliable on till receipts?
On PDF invoices, field accuracy exceeds 95 %. On photos of crumpled receipts, expect 80 to 90 %, which is why a quick staff validation step matters.
Can it connect to Xero or QuickBooks?
Yes, both expose well-documented APIs. A robust connector costs 6,000 to 10,000 GBP and ships in 3 to 5 weeks.
How long until the portal goes live?
Allow 12 to 16 weeks from design to production, including a 2-week pilot with 20 clients before full rollout.
Let's scope your project. Tell us your client count, practice software and current pain points, and we will price a portal between 30,000 and 70,000 GBP delivered in 12 to 16 weeks. Detailed quote within 48 h. WhatsApp +221 77 596 93 33.
Mohamed Bah
Fondateur, Kolonell
Passionate about digital and entrepreneurship in Africa, Mohamed has been helping Sénégalese businesses with their digital transformation since 2020. Founder of Kolonell, he believes every SME deserves a professional and accessible online présence.
