16 KiB
Taffii: A Private Money Pool for Friends and Family
Technical Whitepaper
1. Introduction
Taffii is a private money coordination system for a closed group of approximately 20-30 friends and family members. It automates what could otherwise be managed manually: a shared fund pool with individual ownership tracking.
Taffii is not a public fintech platform, a commercial service, or a consumer-facing product. It is a private arrangement among personally known individuals who have chosen to pool their money for mutual convenience.
This document describes the technical architecture, operational model, and design principles of this private system.
2. System Overview
Taffii digitizes a process that groups of friends and family have used for generations: pooling money into shared accounts while maintaining individual ownership records.
Historically, this might be done with:
- A single bank account opened by one trusted person
- A notebook or spreadsheet tracking who owns what
- Manual coordination of deposits and withdrawals
Taffii automates this arrangement using software. It provides:
- A coordination layer above regulated UK banking services
- Automated ledger tracking of individual ownership
- Digital interfaces for deposits, withdrawals, and balance checking
- Bank-like convenience without being a bank
The system serves a fixed, closed group of personally known individuals. It is not marketed publicly, does not accept general applicants, and has no growth objectives beyond its intended membership size.
3. Design Objectives
Taffii automates a private arrangement that could be managed manually. The system is designed with the following objectives:
- Automate traditional practices: Replace manual ledgers and spreadsheets with software
- Full reserve backing: All member balances are backed 1:1 by funds in regulated accounts
- Explicit ownership: Clear individual ownership of funds at all times
- Bounded risk: System constraints that limit exposure and complexity
- Private operation: Serve a fixed group of personally known individuals, not the general public
4. System Classification
Taffii functions as a private arrangement among friends and family, specifically:
- A closed group fund pool (20-30 members maximum)
- Software automation of manual money coordination practices
- A ledger system tracking ownership of pooled funds
- A technical layer above regulated banking services
What this is not:
Taffii is not a public service or commercial platform. It does not operate as:
- A consumer-facing fintech product
- A deposit-taking institution
- A lending platform
- An investment service
- An Electronic Money Institution (EMI)
- A payment institution offering services to the public
Key distinction: Taffii automates what the group could do manually with a shared bank account and a notebook. The difference is convenience and accuracy, not the fundamental nature of the arrangement.
5. Membership Model
Membership in Taffii is limited to a fixed group of personally known individuals—friends and family of the system operator.
Membership characteristics:
- Fixed size: Approximately 20-30 members maximum
- Personal relationships: All members are personally known to each other or to the operator
- Invite-only: No public applications or open enrollment
- Vetted access: Each member is individually approved through personal vetting
- Shared ownership: Each member retains individual ownership of their contributed funds
Technical enforcement:
The system implements technical controls to maintain its private nature:
- Invite-only onboarding system (already implemented)
- Know Your Customer (KYC) processes for all members
- No public-facing interfaces or marketing
- Hard membership caps enforced at the system level
This is a genuine limited network, not a public service claiming to be private.
6. Custody Architecture
Funds are held in regulated UK bank accounts operated by IMBENJI.NET LTD for the purposes of administering the private group arrangement, eligible for Financial Services Compensation Scheme (FSCS) protection.
Key principles:
- All money remains within FCA-regulated banking infrastructure
- Multiple accounts may be maintained to preserve FSCS protection
- Custody is provided by FCA-regulated UK banks
- FSCS protection applies to the underlying accounts (£85,000 per institution)
Technical implementation:
- Payment operations use TrueLayer's APIs and services
- TrueLayer (an FCA-authorized Account Information Service Provider and Payment Initiation Service Provider) handles payment initiation
- The Taffii software layer provides accounting, allocation, and coordination
- Individual ownership is tracked in the internal ledger system
Operational model:
This arrangement replicates what could be done manually: one person (or entity) opens bank accounts, friends and family transfer money in, and records are tracked of who owns what. Taffii automates the record-keeping and coordination but does not fundamentally change the nature of the arrangement.
Taffii does not itself provide payment services, issue cards, or hold e-money. Custody of funds remains with regulated UK banks, and payment execution is performed exclusively by FCA-regulated third-party providers. Taffii's role is limited to accounting, coordination, and authorization decisions based on its internal ledger.
7. FSCS Protection Strategy
To maintain regulatory protection at scale, Taffii implements an account distribution system:
- Multiple underlying bank accounts are maintained across partner institutions
- An automated administrative process distributes funds across accounts (operational execution, not algorithmic trading)
- Account balances are monitored relative to FSCS protection limits (currently £85,000 per institution)
- When an account approaches protection thresholds, new funds are routed to alternative accounts
Account distribution is an operational safeguard to limit concentration risk and preserve FSCS coverage. Allocation decisions are administrative and do not affect individual ownership as recorded in the ledger.
8. Ledger System
Taffii maintains an internal ledger that tracks:
- Individual member balances
- Allocation of funds across backing accounts
- Transaction history and state changes
Reconciliation process:
The ledger is continuously reconciled against actual bank account balances through automated checks. In the event of discrepancies:
- Automated alerts are triggered
- New deposits may be temporarily paused
- Manual investigation procedures are initiated
- Discrepancies are resolved before normal operations resume
This reconciliation process ensures that the ledger accurately reflects the true state of funds at all times.
Balance Materialization
For performance and availability, the system periodically materializes per-member balance snapshots derived from the append-only ledger. Real-time balance checks (e.g., during card authorization) use the most recent snapshot combined with subsequent ledger deltas. The ledger remains the sole source of truth; cached balances are non-authoritative and can be recomputed at any time.
9. Balance Limitations
The system enforces a per-member balance cap, typically set between £20,000 and £30,000.
Rationale:
- Risk limitation per participant
- Operational simplicity in reconciliation
- Reduced complexity in fund distribution
- Clear scope definition for the system's use case
This cap represents a system design constraint rather than a usage restriction. Members may use the system as they see fit within this boundary.
10. Withdrawal Mechanics
Because the system maintains full reserve backing:
- All withdrawals can be immediately honored
- No queuing or liquidity management is required
- Funds may be aggregated from multiple backing accounts if necessary
Withdrawals are executed through regulated payment APIs provided by partner banking institutions.
11. Cards, Issuing, and Funding Model
Taffii does not itself issue payment cards, hold electronic money, or operate payment rails. Card functionality is provided through integration with regulated third-party payment providers (the "Issuing Partner"), such as licensed card issuers or payment institutions.
Card Issuance
Payment cards are issued by the Issuing Partner under their regulatory permissions and card scheme memberships. The Issuing Partner is the issuer of record and is responsible for authorization, settlement, safeguarding (where applicable), and compliance with relevant regulations and card network rules.
While cards may be presented within the Taffii user interface, they are legally issued and operated by the Issuing Partner.
Funding Model
Taffii operates using a prepaid card model with just-in-time-like funding characteristics:
- IMBENJI.NET LTD maintains a liquidity pool with the Issuing Partner (typically £1,000-£2,000 across all members)
- Individual cards default to £0 balance
- Member balances are tracked in Taffii's internal ledger (separate from card balances)
Transaction Authorization Flow
When a member attempts a purchase:
- The Issuing Partner sends an authorization webhook to Taffii
- Taffii checks the member's ledger balance for sufficient funds (using cached balance snapshots as described in Section 8, with the ledger remaining authoritative)
- If sufficient funds exist, Taffii allocates funds from the liquidity pool to the member's card
- Taffii approves the authorization
- The transaction completes via the Issuing Partner's payment rails
- Taffii updates the member's ledger balance accordingly
Authorization decisions are expected to complete within the card network timeout (~500ms), subject to Issuing Partner capabilities.
ATM Withdrawals
For ATM access, members declare their withdrawal intent through the Taffii interface (e.g., "I need £50 from an ATM"). Taffii then pre-funds the card with the requested amount, allowing the member to complete the withdrawal within a reasonable timeframe.
Liquidity Pool Management
The liquidity pool is periodically replenished from the UK bank accounts when it falls below operational thresholds. This separation allows for:
- Capital efficiency (only maintaining necessary working capital at the Issuing Partner)
- Fast authorization responses (internal reallocation vs. external bank transfers)
- Clear accounting separation between custody (UK banks) and payment execution (Issuing Partner)
Role of Taffii
Taffii's role is limited to:
- Recording member balances in its internal ledger
- Making authorization decisions based on ledger balances
- Communicating funding instructions to the Issuing Partner
- Providing user-facing software for visibility and coordination
At no point does Taffii act as the issuer of stored value or as the final authorizing entity for card transactions. All regulated payment activities are performed by the Issuing Partner.
12. Access Control & Network Limitation
Taffii operates as a genuinely limited network with technical enforcement of its private nature.
Implemented controls:
- Invite system: Members can only join via personal invitation
- KYC processes: All members complete identity verification
- Personal vetting: Each prospective member is individually approved
- Hard membership cap: System enforces maximum of 20-30 members
- No public access: No public-facing website, app store presence, or marketing
- Relationship requirement: All members are personally known to the operator or existing members
Purpose of limitation:
These constraints are not temporary or aspirational. They are permanent design decisions that define what Taffii is:
- A private arrangement among friends and family
- Not a service offered to the public
- Not a platform seeking growth or scale
- Not a commercial venture
The technical implementation of these limitations demonstrates that Taffii is fundamentally different from consumer fintech products or payment services offered to the general public.
13. Functional Limitations
The following capabilities are explicitly excluded from the system design:
- Lending or credit provision
- Investment or asset management services
- Overdraft facilities
- Traditional bank account numbers and sort codes
- Direct debit origination
- Direct salary payment reception (in system's own name)
These exclusions are intentional design choices that maintain the system's scope and regulatory positioning.
14. Regulatory Positioning
Taffii's regulatory status derives from its nature as a private arrangement among a small, closed group of personally known individuals.
Distinguishing characteristics:
- Limited network: Fixed membership of 20-30 people maximum
- Personal relationships: All members are friends/family, not customers
- No commercial purpose: Not offered as a service to the public
- Manual alternative exists: Replicates what could be done with notebook and bank account
- No public marketing: No advertising, no public enrollment, no growth objectives
Comparison to regulated activities:
Traditional payment institutions and EMIs provide services to the public or operate networks open to general participation. Taffii differs in that:
- It serves only personally known individuals
- Membership is permanently capped and controlled
- It automates an existing practice rather than creating new financial services
- Technical controls enforce these limitations (not just policy claims)
Legal structure:
- Operated by IMBENJI.NET LTD, a UK registered company
- Bank accounts held in the company's name
- TrueLayer (FCA-authorized) used for payment operations
- All underlying custody in FCA-regulated UK banks with FSCS protection
Where regulated activities occur (e.g., card issuing, payment execution), these are performed by licensed third-party providers acting in their regulated capacity.
Note on regulatory advice:
This document describes the system's design and positioning. Operators should seek specific legal advice regarding regulatory requirements for their jurisdiction and use case.
15. Design Philosophy
Taffii is built on several core principles:
Automation, not innovation: The system automates what friends and family already do manually. It does not create new financial mechanisms or products.
Transparency: All members understand exactly how the system works—the pooled accounts, the ledger tracking, the custody arrangements.
Constraint as honesty: Hard limits (membership cap, balance limits, functional boundaries) are explicit design choices that define what the system is and isn't.
Verification over trust: Continuous reconciliation ensures that the ledger accurately reflects reality.
Private by design: Technical enforcement of the limited network is not a temporary measure but a permanent characteristic of the system.
16. Conclusion
Taffii is a private money coordination system for approximately 20-30 friends and family members. It automates the record-keeping and coordination that could otherwise be managed with a shared bank account and a spreadsheet.
The system is not a public fintech platform, a commercial service, or a product offered to consumers. It is a closed arrangement among personally known individuals who have chosen to pool their money for mutual convenience.
Key characteristics:
- Operates within regulated UK banking infrastructure (FSCS protection maintained)
- Uses FCA-authorized services (TrueLayer) for payment operations
- Enforces private network status through technical controls (invite system, KYC, membership caps)
- Maintains full reserve backing and continuous reconciliation
- Serves a fixed group with no public access or growth objectives
By automating what could be done manually while maintaining transparency, full backing, and clear ownership, Taffii offers convenience to its small group of members without attempting to replace or compete with traditional banking services or consumer fintech products.
This is fundamentally an arrangement among friends and family, implemented with software.