(Adds detail) BRASILIA, May 31 (Reuters) - Brazil’s public finances improved significantly and across the board in April, official figures showed on Monday, as a chunky budget surplus contributed to the biggest decline in government debt as a share of the economy in over a decade. Public sector debt fell to 86.7% of gross domestic product in April, central bank figures showed, the lowest since July last year and down sharply from 88.9% the month before. The decline of 2.2 percentage points was the steepest month-on-month fall since December 2010, according to Refinitiv data. Net public sector debt also fell in April, to 60.5% of GDP from 61.1% the month before. That was the lowest since October. Stronger-than-expected tax revenues in recent months have helped brighten the outlook for Brazil’s public finances, so much so that Economy Minister Paulo Guedes said last week that the overall budget deficit could swing to surplus as early as 2023. The central bank’s figures on Monday showed that the public sector registered a surplus in April excluding interest payments of 24.3 billion reais ($4.7 billion), more than the 16.75 billion reais surplus forecast in a Reuters poll of economists. The nominal surplus in the month including interest payments was 30 billion reais, the central bank said. The accumulated primary deficit in the 12 months through April was 544.5 billion reais, or 7.1% of GDP, the smallest deficit since June last year and below a downwardly revised 8.8% of GDP in the year through March, the central bank said. The nominal deficit including interest payments in the year through April was 827.2 billion reais, or 10.8% of GDP, the central bank said, compared with 973 billion reais, or 12.9%, of GDP the month before. $1 = 5.22 reais Reporting by Jamie McGeever; Editing by Alison Williams and Steve Orlofsky Our Standards: The Thomson Reuters Trust Principles.