Bengaluru, Dec. 5 -- The rupee's fall to a historic low against the US dollar on Wednesday has left one segment of companies cheering -India's $283 billion information technology (IT) sector. The rupee plunged to 90.29 against the US dollar before closing at 90.19, marking a fall of 5.4% since the start of the fiscal year. India's tech sector benefits from this because its export receipts translate into more rupee revenue. In contrast, importers have to shell out more rupees for their dollar buys. IT firms including Tata Consultancy Services Ltd, Infosys Ltd, HCL Technologies Ltd, and Wipro Ltd get over 40% of their business from the US, for which they are paid in dollars. Even as the higher-valued dollar is a positive for the sector, other currencies are also expected to help. Since the start of the year, the rupee has declined 15.47% to Rs.120 per pound and 8.32% to Rs.105 against the euro. Indian IT's Big Five get 25 to 33% of their revenue from Europe. Mumbai-based TCS reportedly gets 17.5% of its revenue from clients in the UK. None of the other top five Indian IT firms disclose UK revenue separately. The rupee's fall comes as a boon for the IT sector, which has grown at its slowest clip in decades because of low demand amid high lending rates, which has curbed client spending. Revenue has taken a hit with automation tools resulting in lower billing. "In a scenario where the macroeconomic environment has been uncertain but on an improving trajectory, a depreciating Indian rupee will act as a positive cushion for the IT sector," said Amit Chandra, vice president of HDFC Securities. Only three of the Big Five ended last year with revenue growth, which did not exceed 5% on a yearly basis. TCS' revenue rose 3.78% to $30.18 billion, Infosys reported a 3.85% growth to $19.28 billion and HCLTech ended with a 4.3% increase to $13.84 billion. Wipro ended with a 2.72% drop in revenue to $10.51 billion and Tech Mahindra's revenue fell 0.21% to $6.26 billion. However, the bigger impact of the depreciating rupee is expected to be on the profitability of IT services companies. "Every 1% decline in the value of the rupee is expected to contribute 10-15 bps (basis points) of margin expansion," said Chandra. On paper, a decline in value against the dollar, the euro and the pound implies an at least 420 bps boost in the sector's operating margin. However, cross-currency fluctuations, wage hikes, fewer working days, restructuring costs and client-specific expenses are expected to drag down the operating margin. The higher value of the dollar, the euro, and the pound is expected to significantly increase the rupee revenue of domestic tech services companies. This is margin accretive, according to a second analyst. "A depreciating rupee impacts Indian IT services providers positively because while their revenues are in foreign currencies, a majority of their costs are in rupees," said Ashutosh Sharma, vice-president of Forrester Research. The major expenses of Indian tech service providers include employee salaries and rent for office spaces. These are incurred in rupees and do not change on favourable currency movements. This implies that technology services providers will have more money in rupees after these costs and therefore, higher operating margins. For the big boys of Indian IT, a weak rupee will help offset the higher costs of obtaining visas for foreign workers employed by US companies. On 19 September, US president Donald Trump increased the visa fees for new applications to $100,000, a 10-fold jump. This is expected to increase costs and dent margins for Indian IT services companies. In such a scenario, a declining rupee is expected to marginally offset the hit on operating margins. Each of the country's top five IT services companies has acknowledged that currency tailwinds are a key margin contributor. At the end of September, the margin benefit from the declining rupee was 80 bps to 25.2% for TCS, 60 bps to 21% for Infosys, 56 bps to 17.5% for HCLTech and 40 bps to 12.1% for Tech Mahindra. Wipro, the fourth-largest IT services provider, ended the quarter with an operating margin of 16.7%. It cited the "positive" impact from favourable currency movements, without specifying the exact effect....