The Association of Investment Companies said it was the first time HMRC had withdrawn the status of a VCT at the time when it occurred.
Pleas from the company led to HMRC reviewing the original decision.
A Stock Exchange announcement has been made to confirm permanent reinstatement.
An Oxford Technology statement read: "We are now pleased to be able to confirm that the corrective steps proposed by our legal advisors have been successfully completed and HMRC have been so informed.
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"We have received formal acknowledgement from HMRC that the corrective action taken has been sufficient and that we will now retain VCT status going forward subject to continued compliance with VCT rules.
"This means that the tax reliefs previously given to the VCT and its shareholders will not be disturbed, and the entitlement to benefit from future reliefs available to VCTs will likewise continue."
It said the VCT's holding in Scancell is now as it was prior to July 2013 and the HMRC action resulted in no financial gain or loss to the VCT.
The firm's statement added: "We wish to record our appreciation for the constructive way in which HMRC have engaged with us during the last six months."
The company had originally informed HMRC of its own mistake, saying it had exceeded the maximum threshold of 15 per cent that a VCT fund can invest in any one company.