The Glasgow company is being backed by RBS and has approval on a £250,000 regional selective assistance grant from Scottish Enterprise.
UC chairman Alf Gordon, who took a £33m share when Aberdeen engineering business Qedi was sold last year, has put in £1m to fund the venture.
Joanna Holloway, formerly with RBS invoice finance and First Direct, has been appointed managing director and she estimates there are around 1.6 million potential customers in the UK for UC's services. A soft launch to test processes and systems involving 12 customers has gone smoothly and the company hopes to attract 300 clients in its first year.
It allows contractors to borrow up to 80% of the value of a timesheet.
Ms Holloway said: "We are trying to control the growth so are keeping our projections quite modest.
"The forecast is that by year three we will have 1000-plus clients. When you look at the size of the market the numbers could be significantly higher but the processes we have can be scaled up quite easily.
"This is a growing community in the UK which is being denied access to the finance they need.
"Our business will be ethical and transparent. Our costs are comparable with that of an overdraft and are favourable when compared with other forms of short-term lending.
"We are plugging a gap by lending to small businesses which otherwise would not get funding."
Ms Holloway said UC also hopes to free contractors up from some business administration tasks.
Ms Holloway added: "We will cover a wide range of industries. It could be media, oil and gas, renew-ables, banking, financial sector or IT. The crucial thing is they are limited company directors with a contract for services.
"We do our due diligence against the contractor and the end user client who will pay the invoice. Once the contractor is our client they email us their timesheet whenever they get it. They then get 80% of the value of the timesheet upfront and we invoice on their behalf so it saves on their admin."
UC employs a small team at the moment but expects to create 10 jobs in its first year and 36 over the next three years.
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