Finance Minister Nhlanhla Nene is expected to keep his budget deficit target unchanged from October forecasts.
(READ MORE: S.Africa’s real GDP up 4.1% in Q4 2014 – STATS SA)
South Africa's has been dogged by the uncomfortably high fiscal and budget deficits recently, often putting the currency under pressure in times of heightened global risk aversion.
At 0710 GMT, the rand was at 11.4725 against the dollar, unchanged from last night's close in New York.
The rand failed to make further gains overnight after receiving a lift on Tuesday supported by better-than-expected fourth quarter economic growth numbers.
Traders cited caution hours before the budget speech.
"Of course all eyes and most importantly those of the credit rating agencies will be on the local budget speech this afternoon," said Warrick Butler, a trader at Standard Bank.
"The most important details to look out for will be the forecasts on the twin deficits as well as their growth forecasts. Tax hikes are almost a given," he added.
(READ MORE: S.Africa’s budget highlights urban and housing development)
Economists polled by Reuters expect Nene to announce a budget deficit target of 3.6 per cent of gross domestic product for the fiscal year starting in April.
Bonds were firmer with the yield on the benchmark government bond maturing in 2026 down one basis point to 7.555 per cent.