Commonwealth Bank expects the RBA to raise rates 25bp to 4.35% in May 5, but warns the decision is line ball given Iran war inflation pressures and softening consumer sentiment.Summary:Commonwealth Bank of Australia economists forecast the RBA will raise its cash rate by 25 basis points to 4.35% at its May board meeting, but described the decision as line ball and more precarious than the March hikeThe case for a hike rests on inflation remaining too high, a labour market still too tight at 4.3% unemployment, and cost pass-through from the Iran war accelerating faster than expected, per CBAThe case for holding has strengthened since March, with trimmed mean CPI printing at 0.8% for Q1 2026, below expectations of 0.9%, alongside sharp falls in business and consumer sentiment and emerging cracks in the Sydney and Melbourne housing markets, per CBACBA expects the RBA's updated Statement on Monetary Policy to forecast lower GDP growth, higher inflation peaking at 5.1% headline and 3.8% trimmed mean, and higher unemployment, all driven by the Iran war and the higher cash rate profile, per CBAThe RBA's February oil price assumption of $64 per barrel has been overtaken by Brent sitting around $110, while the Australian Trade Weighted Index is approximately 3% higher and the cash rate profile is around 60 basis points above the February forecast peak, per CBAAfter May, CBA expects the RBA to remain on hold as the economy slows under the combined weight of three rate hikes and elevated energy prices, though a swift resolution to the war and lower energy prices would increase the risk of further tightening, per CBAMarkets were pricing approximately a 75%+ probability of a May hike at the time of writing, per CBACommonwealth Bank economists are tipping the Reserve Bank of Australia to lift its cash rate by 25 basis points to 4.35% at the May board meeting underway, but have described the decision as another line ball call, warning that the meeting feels more precarious than the hike delivered in March.The central complication is the Iran war. Since the conflict began with US and Israeli airstrikes on Iran on February 28, Australia has experienced three distinct knock-on effects: a sharp deterioration in business and consumer confidence, a wave of businesses announcing higher costs and fuel surcharges, and early signs of rising inflation expectations. CBA economists note that the RBA's February oil price assumption of $64 per barrel has been comprehensively overtaken by events, with Brent crude now sitting $110+, a gap that is feeding directly into transport and material costs and accelerating price pressures across the economy.The case for hiking centres on inflation that remains above target with an economy still running above capacity. Inflation expectations are rising across both consumer and market measures, and unions and the federal government have both flagged support for a 5% lift in minimum and award wages, which CBA sees as adding to the urgency of anchoring expectations. A labour market with unemployment at 4.3% remains too tight to bring inflation back to target without further policy action, and lingering uncertainty over how restrictive the current cash rate actually is adds a further argument for tightening.But the dissenting case has gained ground since March. Trimmed mean CPI for Q1 2026 came in at 0.8% per quarter, below RBA, market and CBA expectations of 0.9%, with the miss driven largely by softer travel prices. Housing markets in Sydney and Melbourne have shown steeper price falls, sentiment surveys have deteriorated sharply, and with three rate hikes already delivered alongside higher energy costs, the cumulative drag on economic activity is beginning to show. CBA's internal spending data reflects a tentative consumer rather than one in clear distress, but the direction of travel is downward.CBA expects the RBA's updated Statement on Monetary Policy forecasts to reflect the changed environment, projecting lower GDP growth, higher inflation peaking at 5.1% on a headline basis and 3.8% for trimmed mean, and a higher unemployment path. The bank expects trimmed mean inflation to fall back below 3% only by the second quarter of 2027, driven in part by unemployment rising to 4.6%, a timeline that CBA notes carries additional costs for the labour market if brought forward.After May, CBA anticipates the RBA will move to the sidelines as the economy absorbs the combined weight of the tightening already delivered and persistently elevated energy prices. A swift resolution to the Iran conflict and a consequent fall in energy costs would be the key factor capable of reopening the debate about additional hikes later in the cycle.---A third consecutive RBA rate hike would reinforce the hawkish signal already embedded in Australian fixed income markets, with the cash rate potentially reaching 4.35% at a moment when the Iran war is still actively pushing energy and transport costs higher. CBA's forecast that headline CPI peaks at 5.1% and trimmed mean at 3.8% suggests the inflation problem is far from resolved, which limits the scope for any dovish pivot even if the board ultimately opts to hold. For energy markets specifically, the note underscores how the Hormuz closure is transmitting directly into Australian monetary policy, with the RBA's February oil price assumption of $64 per barrel now sitting roughly $46 below prevailing Brent levels. The Australian dollar's resilience above $0.70 provides some partial offset to import cost pressures, but CBA does not expect that to be sufficient to delay tightening. This article was written by Eamonn Sheridan at investinglive.com.