How to Issue Business Tax Receipts Through WhatsApp | Ernest (Simplify VFD Tech Lead)
Atoms & Bits Interview #4
Tanzania's path to digital tax compliance began in 2010 with physical Electronic Fiscal Devices (EFDs) costing upwards of TZS 350,000.
Today, a new generation of cloud-based solutions is transforming how businesses handle tax receipts and compliance.
Among them is Simplify VFD, which has grown to serve over 1,800 enterprises with a digital platform that costs TZS 142,780 for setup and TZS 69,620 annually.
In a November 28 interview with Atoms & Bits, Ernest Mwinchumu, Simplify's Tech Lead, offered insights into building and scaling a tax compliance platform in Tanzania.
Having joined as a software developer in 2022, Mwinchumu has helped guide the company's technical evolution from a simple receipt generator to a comprehensive compliance solution that now processes thousands of transactions daily through web, mobile, and WhatsApp interfaces.
This technical deep-dive explores how a local engineering team tackled challenges in data security, API integration, and accessibility while maintaining a renewal rate above 85%.
It also examines the realities of building software products in Tanzania, from recruiting technical talent to choosing technologies that work within local infrastructure constraints.
What drew you to join Simplify as a software developer in 2022?
I've been passionate about technology since childhood, even battling through family situations to stay in tech.
When I met Baraka (Cassian, our Founder & Managing Director) in 2022, he shared a vision of building a local solution for Tanzanian businesses. As the first local technical hire, I saw an opportunity to prove that Tanzanian developers could deliver value.
Initially, Baraka was skeptical about working with local engineers, which motivated me to demonstrate what we could achieve.
What factors have contributed most to your growth from developer to tech lead?
Growth doesn't happen in isolation. I've been fortunate to work with an amazing team, both locally and internationally.
Our directors and business team have created an environment where I could gradually take on more responsibilities.
When I started as the first local technical hire, they supported my development even though there was initial skepticism about local talent. The team's trust allowed me to prove myself through reliable delivery and technical leadership.
How does Simplify VFD work from a technical perspective?
Our platform allows businesses to issue tax receipts through multiple channels.
The core function is simple: you enter customer details, product information, and payment data.
We've built this using Vue.js for the user interface and PHP for the backend (data storage, processing, etc.).
Simplify VFD automatically handles integration with TRA (Tanzania Revenue Authority) systems and can process up to 6,000 receipts daily.
For larger enterprises, we provide API access that automates the entire process, particularly useful for companies issuing hundreds of receipts daily.
What drove your technical decisions when building the infrastructure?
We focused on efficient development that could deliver high quality at low cost.
By implementing micro-services architecture early, we ensured each component could operate independently while remaining tightly coupled when needed.
The most critical service, which is interaction with TRA's systems, runs as a separate module. This approach helped us scale from handling a few receipts to thousands daily without significant downtime.
Tell us about your development environment and how you prevent system issues
We maintain multiple environments for testing features before they reach users. New code first goes through internal testing, then moves to additional environments for verification before reaching production.
Every developer must create a separate branch for new features. I learned this importance early when I once pushed directly to the master branch and nearly caused system downtime.
Now we have strict protocols where changes require review before deployment. This multi-stage process helps us maintain reliability while shipping new features regularly.
How do you maintain development velocity while ensuring reliability?
Instead of traditional product review meetings, we operate with continuous feedback.
Our technical team includes: two backend engineers and myself as primarily a frontend engineer, plus another person who does frontend and UI/UX.
When implementing new features, developers test internally first. If our own team gets excited about using a feature, it's likely to succeed externally too.
Your platform processes sensitive financial data. How do you handle security?
We implement multiple security layers, including two-factor authentication and role-based access control.
Even within our team, access to customer data is strictly limited. Many on the business side have no access to the technical systems.
In addition, we've been through numerous security audits conducted by private partners and regulatory bodies.
For clients using our API, we provide detailed technical support. From initial integration through to production, ensuring their systems maintain security standards while automating receipt generation.
With annual subscription at TZS 69,620 compared to traditional EFD machines costing over TZS 350,000, how do you maintain quality while keeping costs low?
We achieve this through efficient development practices and cloud infrastructure optimization.
Modularizing our services and implementing well-diagrammed architectures are among the methods we use to keep operational costs manageable.
But the key is volume. We focus on reaching as many businesses as possible rather than maximizing revenue per customer. This strategy has worked well, leading to a high subscription renewal rate.
We've also invested heavily in customer support, opening agents in multiple regions to maintain service quality.
How do you handle large businesses that need to issue hundreds of receipts daily?
For businesses with high transaction volumes, we offer API (application programming interface) integration.
That allows their existing accounting or ERP software to automatically issue tax receipts.
When a company creates an invoice and receives payment, the system automatically generates a compliant tax receipt. This automation is particularly valuable for VAT-registered businesses, as it provides a single source of truth for tax filing and helps prevent costly penalties.
While the API pricing follows an enterprise model different from our standard subscription, we keep it accessible through custom arrangements based on usage patterns.
You recently added WhatsApp as a distribution channel. What technical challenges did you face?
The main challenge was ensuring accuracy in a chat interface where errors could have serious compliance implications. We implemented extensive validation systems since users might accidentally add an extra zero when typing on their phones.
Before submitting any receipt, the system shows a comprehensive summary including all amounts, names, products, and especially the tax calculations. This gives users a clear chance to verify everything before submission.
The WhatsApp integration uses Twilio for messaging and operates as a free add-on for existing clients who might need to issue receipts when they can't access the main platform.
What specific measures do you take to prevent unauthorized use of tax receipts?
We implement strict verification to prevent ghost vendors - a situation where someone might get a business's TIN number and issue unauthorized receipts.
Every new business must complete KYC with director's ID, verify their account at the local tax office, and submit proper business registration documents.
This three-level verification helps ensure receipts are only issued by legitimate authorized businesses.
How do you manage your week as a technical lead while still contributing to development?
I dedicate specific days, usually Wednesdays and Thursdays, for core development work.
Our team has three weekly catch-ups. Monday for planning, midweek for progress checks, and Friday for review. We also hold joint sessions with the business team to align product development with user needs.
If meeting a deadline requires extra time, I'll work late, but we encourage early communication about timeline challenges.
When I have extra time, I invest it in learning new stuff like mobile development to add to our company's existing skill sets.
How are you approaching the development of technical talent in Tanzania?
The first step is helping people find their specific passion within technology. The field is vast, from frontend to mobile to backend development.
I advise newcomers to analyze these different roles and identify where they fit best rather than trying to learn everything.
The internet provides abundant resources, so there's no excuse not to grow in your chosen specialty. The goal is to become known and relied upon for excellence in a specific area rather than being average across many skills.
You mentioned building with local talent despite initial skepticism. What's working in your recruitment approach?
Our success comes from leading with vision rather than just compensation. And recently, we recruited a talented female engineer from a pool of over 20 applicants.
While startups can't always match corporate salaries, we offer two key things: a clear vision of becoming Tanzania's go-to compliance platform, and well-defined company processes that make engineers comfortable.
When technical people see their place in that vision early, they become passionate contributors to our growth.
Looking at your customer base, what patterns are you seeing in how businesses adopt digital compliance?
We see varying levels of feature utilization.
Some businesses, regardless of size, embrace advanced features like our multi-user system, which allows up to 20 field agents to issue receipts across the country under one account.
Others stick to basic receipt generation and sales reporting. The key difference isn't company size but rather their digital maturity and willingness to automate processes.
Through our API, we're particularly seeing interest from multi-merchant platforms that want to integrate tax compliance directly into their systems.
What's your approach to making tax compliance accessible across Tanzania?
We recognize that access to digital tools varies widely across the country.
Our web and mobile apps serve urban areas with good internet connectivity. But we've also developed alternatives like USSD access for areas with limited smartphone penetration.
Each receipt requires just two key pieces of information—customer details and transaction data—so we've made the process as streamlined as possible.
We also automatically send customers SMS links to their digital receipts, bridging the gap between analog and digital systems.
What advice would you give to computer science students in Tanzania?
Look at how you present yourself professionally.
Your CV as a technical person needs to be different from a business CV. Showcase your projects, education, and work experience clearly.
Many talented developers exist locally, but we need to improve how we communicate our capabilities.
Whether on LinkedIn or in person, make sure people can immediately understand your technical passion and expertise. Every person you meet could be a future colleague, employer, or employee.
Which software engineers in Tanzania inspire you the most?
I've connected with a few technically strong people here in Dar.
I really admire a very good friend of mine who I work with a lot called Louis Ngatale.
He's working with Safiri and has been a very good developer for the past four or five years. Whenever there's something I need to learn, I reach out to him.
I've also spoken to Prosper Absalom from Swahilies. While we haven't had many deep conversations, I really appreciate how technical he is and how he expresses himself professionally. Harun Kimaro, another friend at CRDB Bank, also exemplifies the kind of talent we have locally.
What makes these engineers special is their eagerness to keep learning while remaining reliable in getting stuff done.
I hope to meet more mentors, and I encourage experienced technical people to share their knowledge. There are many willing to learn, and having mentors is crucial for growth in our tech community.